T T 




SCHOOL SHOP 
INSTALLATION 

AND 

MAINTENANGE 




GREENE 



miHMiMiitj ii 




Book 



Gpightl^i 



CX2E0UGHT DEPOSm 



SCHOOL SHOP 

INSTALLATION AND 

MAINTENANCE 



L. S. GREENE, M.S. 

V 

State Supervisor Industrial Education, Florida 

Professor Industrial Education, University of Florida 

Formerly 

Assistant Professor of Industrial Education, 

University of Wisconsin 




THE MANUAL ARTS PRESS 
f PEORIA, ILLINOIS 



/<\>»'^ 

^ (^ 



Copyright, 1922 
L. S. Greene 

I2D22 



Printed hi the United Slates of America 

MAY - 1-1922 



PREFACE 

THE author has observed that among teachers of shop sub- 
jects there is a noticeable lack of abihty when it becomes 
their duty to solve problems of school shop planning, installation 
and maintenance. 

The fundamental reason for this deficiency is, perhaps, that, 
altho there are numerous technical books and magazine articles 
deaHng with such problems, they are written primarily for the 
engineer and do not provide readily the comparatively simple, 
yet essential information needed by the shop teacher when it 
becomes his duty and privilege to plan, install and keep in order 
school shop equipment. 

The purpose of this book is therefore two-fold. An attempt 
has been made to present in simple language and readily usable 
form, information, rules and methods that (1) will constitute a 
handbook for teachers for use in solving these problems of equip- 
ment and maintenance, and (2) will be a text for use in normal 
courses in which manual arts and vocational teachers are trained. 

While the material presented in these notes may be of greatest 
use to shop teachers as a handbook and to teachers of vocational 
teacher-training classes, these two purposes do not limit its use. 
For instance, pupils in many vocational classes should know how 
to take care of belting properly, how to babbitt a bearing, how to 
fit circular saws, braze bandsaws, etc., and in this sense this book 
can be used as a text and reference book by the students. Because 
of the direct method of presenting the subject matter, the book 
should also prove valuable to apprentices and mechanics. 

The author wishes to express his indebtedness to Prof. F. D. 
Crawshaw for timely suggestions. The author's wife and associate 
teachers have also been of much assistance. 

The illustrations are the work of the author. 
University of Wisconsin, 1921 L. S. G. 



CONTENTS 

PART ONE— INSTALLATION 

Chapter I. Power Transmission in a School Shop . . 7 

1. Individual vs. group drive; 2. Advantages of individual drive; 
3. Advantages of group drive; 4. Selection of shafting; 5. Speeds 
of line shafts; 6. Rules for determining speeds; 7. Position of 
shafting; 8. Hangers; 9. First alignment, hangers and shaiting; 
10. Fastening hangers; 11. Second alignment; 12. Set collars; 
13. Aligning pulleys; 14. Pulleys and couplings; 15. Placing 
pulleys; 16. Shaft couplings; 17. Rules for finding sizes and 
speeds of pulleys. 

Chapter XL Motors and Currents 24 

18. General considerations; 19. Two types of work; 20. Ad- 
vantages of A. C. motors; 21. Advantages of D. C. motors; 
22. Data required in determining the choice of motor; 23. Plan- 
ning for motor drive; 24. Installation of electric motors; 25. 
Care of motors. 

Chapter III. Installation of Metalworking Equipment 28 

26. General considerations; 27. Planer; 28. Lathes; 29. Drill 
press; 30. Milling machine; 31. Shaper; 32. Forge; 33. Anvil; 

34. Blower. 

Chapter IV. Installation of Woodworking Equipment 33 

35. General considerations; 36. Speeds of various machines; 
37. Emery wheel speeds; 38. Circular-saw speeds; 39. Horse- 
power required for woodworking machines; 40. Other factors to 
consider. 

PART TWO— MAINTENANCE 

Chapter V. Fitting Edge Tools 39 

41. Plane irons; 42. Chisels; 43. Turning tools; 44. The 
draw-knife; 45. Spokeshave blades; 46. The outside gouge; 
47. The inside gouge; 48. Cabinet scrapers; 49. Planer and 
jointer knives. 

Chapter VI. Fitting Saws 47 

50. Hand rip-saw; 51. Hand crosscut-saw; 52. Keyhole-saw; 
53. Miter- and back-saws; 54. Band-saws; 55. Circular rip- 
saws; 56. Circular crosscut-saws. 



6 CONTENTS 

Chapter VII. Brazing Band Saws. . . . o . . 57 

57. Brazing. 

Chapter VIII. Belting 61 

58. Belt comparisons; 59. Choosing a belt; 60. Care of belts; 
61. Applying belts to pulleys; 62. Joining belts; 63. Lacing 
2" to 4" belt with rawhide; 64. Other rawhide laces; 65. Heavy 
work on large pulleys; 66. Lacing with wire; 67. Patent fas- 
teners; 68. Cemented splices; 69. Don'ts; 70. To find the 
horse-power which a belt will transmit; 7L To find width of belt 
required for a given horse-power; 72. With horse -power and 
width of belting given, to find diameter of driven pulley required; 
73. To find the length of belt wanted; 74. To find the horse-power 
of a driving pulley. 

Chapter IX. Babbitting 77 

75. Babbitt metal; 76. Preparing to pour babbitt metal; 77. 
Alignment of the shaft; 78. Preparing the shaft; 79. Damming 
up the box; 80. Melting the metal; 81. Pouring the metal; 82. 
Scraping the babbitt. 

Chapter X. Adjustments of Woodworking Machines . 88 

83. The circular-saw; 84. The jointer; 85. The surfacer; 86. 
The mortiser; 87. The band-saw; 88. The lathe; 89. Play in 
bearings. 

Appendix 95 

Organization of the Preceding Material for Teaching Purposes. 



PART ONE— INSTALLATION 

CHAPTER I 

Power Transmission in a School Shop 

1. Individual vs. Group Drive. — There are two common 
methods of driving machines. One consists in connecting the source 
of power to a Hne shaft from which the individual machines re- 
ceive their power by means of belting and pulleys. This system is 
called group drive. The other method consists in connecting a 
machine directly to a source of power and is called individual drive. 
In the second case, an electric motor is generally used for the power 
and, in the following discussion of individual drive, such power 
will be assumed. 

It is not necessary, of course, that the machines be driven by 
either method alone for the nature of the work to be done or the 
equipment to be used may make it desirable to combine these 
two methods in the same shop so that part of the equipment is 
run as group and part as individual drive. Determination of the 
method to be used should come only after careful consideration has 
has been given to the advantage of each type and after a thought- 
ful survey has been made of the machines to be driven, the work 
to be done on them, and the comparative amount of time that 
each will be in use. 

2. Advantages of Individual Drive. — In the individual drive 
type of power transmission, there is often obtained a decided saving 
in the amount of floor space necessary for different machines. 
It is not necessary to locate the machines in a line or in a certain 
order or so that they will face the same way. This often permits 
of better aisle arrangements and better use of daylight for the 
operation of the machines. The absence of complex overhead 
shafting, pulleys and speeding belts allows of better Hghting, 



8 SCHOOL SHOP INSTALLATION 

avoids collections of dust and oil which fall down on the machines 
and the work, and removes much of the dangers attendant upon 
an industrial shop because of fast turning belts and pulleys. 

If the work being done is intermittent in nature and the 
machines are not all running all the time or at full capacity all 
the time, as is the case in nearly all school shops, then there is a 
saving in the cost of operation and upkeep of machines, shafting 
and belting. There are fewer delays of all machines by breakdown 
of belts, loosening of pulleys, etc. In a wood shop or a metal 
shop, it is often desirable to run the band-saw, drill-press or some 
other machine without necessitating the running of a complete 
line shaft, and possibly other machines with it, and this is not 
necessary if the individual type of transmission is used. Machines 
are made more portable by individual drive and more variation 
of speed for the work to be done is possible. Some machines can 
function properly with the motor connected direct to the main 
shaft, as in the case of the band-saw or small circular-saw, and thus 
the annoyances obtained from the slipping of belts is avoided. 
The energy of the teacher is conserved because of the fewer repairs 
necessary with the result that more efficient instruction should 
obtain. 

The following reasons why individual motor driven machines 
are preferable in schools are given by The Oliver Machinery Co., 
Grand Rapids, Mich. 

1. Because they are more sanitary. 

a. Less belting causes less dust. 

b. Less belting affords more light. 

c. No oil drippings from overhead bearings. 

2. Because they are safer. 

a. No belting to get tangled in. 

b. No belts to break and fall down. 

c. No overhead shafting or other material to be pulled down. 

3. Because they are less noisy. 

a. No belts or shafting to create noise. 

b. Only machines in actual use make any noise at all. 

4. Because they require less attention from instructor, assuring 

better instruction. 

a. Less parts to adjust. 

b. Fewer bearings to lubricate. 

c. Fewer belts to keep tight and in shape. 



POWER TRANSMISSION 9 

d. Fewer disputes with students because they have less chance for 
mischief. 

5. Because they individualize each student's operations. 

a. Students become masters of their own realm. 

b. No time lost because of another's carelessness. 

c. Better discipline is possible because of less opportunity for. 
intercommunication. 

6. Because of less wear and tear — upkeep is cheaper. 

a. No unnecessary running parts — belts, shafts, bearings — hence 
fewer repairs. 

b. Machines will last longer because: 

(1) During class hours, only machines in actual use are running. 

(2) At odd times such as after school and on Saturdays, only 
machines needed are run. 

7. Because operating cost is less. 

a. Less oil, waste and belting is used. 

b. Less current used because power required merely when doing 
actual work. 

8. Because the sytem is more flexible — saves room. 

a. Machines may be located as suits the room and utility, without 
regard to direction of shafting. 

b. Future additions or alterations are more easily performed. 

3. Advantages of Group Drive. — The initial cost of group 
drive is often much less than that of individual drive and with 
certain machines or groups of machines this method might be 
more acceptable as far as cost of operation is concerned. This is 
plain in the case of a number of wood lathes, driven from one line 
shaft, where the total horse-power needed at any one time is less 
than the sum total of the maximum horse-power of the several 
machines. While each machine needs, under certain conditions, 
its maximum horse-power, yet very seldom, and perhaps never, 
would conditions be such that all machines would be using their 
maximum horse-power at the same time. It is safe to assume that 
the power necessary to drive this Hne shaft under these conditions 
would be from 40 per cent, to 80 per cent, of the sum total of the 
maximum horse-power of all lathes on the shaft. If these lathes 
were driven by individual motors, a greater total amount of horse- 
power would have to be provided to drive them. In the case of 
machines, like the lathes mentioned above, where nearly all, or all, 
are driven at the same time, there is economy in the group drive. 
Wherever the machines are small and require Httle power, or where 
the initial cost of individual drive might over-balance the operative 



10 SCHOOL SHOP INSTx\LLATION 

economies of the same drive, it might be advisable to install group 
drive transmission. 

4. Selection of Shafting. — Cold-rolled steel is generally used 
for shafting up to 3" in diameter and is considered to be about 
15% stronger than turned steel shafting. It is round and straight 
and needs no turning unless key-ways are to be cut in it, in which 
case the tension on the surface is relieved, and it may take a form 
not perfectly round. 

In selecting shafting, one should consider not only immediate 
needs but also possible needs of the future; such as adding to the 
amount or the size of the machinery that is to be driven by the 
shafting, increasing the size of the driving motor, or the erection of 
secondary shafting, (i. e., another shaft to be driven by the shaft 
receiving the power by being belted to it) , for the choice of the size 
of a shaft should depend upon two things (1) its abiUty to withstand 
twisting forces when it receives and transmits power, and (2) 
its abihty to remain stiff or to resist bending forces due to the 
weight of the shaft itself, weight of pulleys, pull of belts and dis- 
tance apart of hangers. Should more demands upon the shafting 
be expected in the future, then it is wise to consider these probable 
demands when making a choice of shafting, for thus a saving in 
time, annoyance and money may often be effected. 

As it is not possible to know exactly what additional pulleys, 
machines and power will be needed in the future or what shifting 
and changing of machines and pulleys will take place, it is im- 
possible to determine exactly the size of the shaft. Undoubtedly 
the best poUcy would be to play safe by choosing a shaft slightly 
larger than apparently seems necessary, according to tables that 
will follow, for the extra cost will be justified as a precaution 
against a possibility of adding extra hangers, new bearings, or 
even a larger shaft at a later date, any of which would probably 
cost more than an extra size of shafting when first installed. 

Another point to think about and investigate is whether the 
immediate demands upon the shaft are what might be called normal 
or usual demands, i. e., hangers a usual distance apart, the pull 



POWER TRANSMISSION 11 

of the belts in such a direction as to offset one another, pulleys 
close to hangers, etc. If the condition as regards these points 
is such as to increase the bending tendency of the shaft then the 
shafting should be larger to make up for this tendency even if 
the power to be received or transmitted does not seem to require a 
larger shaft. The tables which follow are guides only and not hard 
and fast rules and one should bear this in mind when using them. 

Where there is a long stretch of shafting and where the de- 
mands upon the shaft, at the far end away from where the power 
is received or transmitted to secondary shafting, are not so heavy 
as at the other end, there is some economy in reducing the size of 
the shafting at this far end. This can be done at a coupling by 
reducing the size of the larger shaft to that of 'the smaller shaft so 
that both of them fit the same coupling. 

Weight for weight a hollow shaft is stronger than a solid one, 
but where the diameters are the same the soHd one is the stronger. 
A shaft will deliver more power at fast speed than at slow, and the 
diameter required to deliver a certain horse-power at fast speed 
is less than that required for the same horse-power at slow speed. 
A shaft, equal in diameter to another but running twice as fast, 
will transmit twice as much power, or in other words, the horse- 
power is directly proportional to the number of revolutions per 
minute of the shaft. 

5. Speeds of Line Shafts. — For machine shops, 120 to 240 
R: P. M. 

For woodworking shops, 250 to 300 R. P. M. 
(R. P. M. means revolutions per minute.) 

6. Rules for Determining Horse-Power. — A shaft which carries 
a receiving pulley or a transmitting pulley for driving another line 
should be considered a prime mover or head shaft when the rules 
which are to follow are used. 

To determine the horse-power {H. P.) transmitted by cold-rolled 
steel shafting at dijfferent speeds as prime movers or head shafts 
carrying the main driving pulley and well supported by bearings 
use the following formula: 



12 



SCHOOL SHOP INSTALLATION 



H. P.= 



d^R 



where d = diameter of shaft in inches, i? = R. P. M. 



100 
of the shaft and H. P. = horse-power transmitted. 

As an example, determine the horse-power transmitted by a 
shaft 2" in dia. running 300 R. P. M. Using the formula above and 
substituting for the letters the figures given in the example we 



get H. P. = 



2X2X2X300 
100 



= 24. 



Below is a table giving various combinations of H. P. 
and diameters. 



R. P. M., 



Applications of the Above Formula 



Dia. of Shaft 



1%. 

m. 

iWe 
2. 

2%. 
2H- 
2?r6- 

2H. 

2%. 
2%. 
2%. 
2>i. 
2%. 
2%. 
2% 



Horse Power 



100 
R. P.M. 



3.4 

3.8 

4.3 

4.8 

5.4 

5.9 

6.6 

7.3 

8.0 

8.8 

9.6 

10.5 

11.4 

12.4 

13.4 

14.5 

15.6 

16. 8 

18.1 

19.4 



200 
R. P. M. 



6.7 
7.6 
8.6 
9.6 
10.7 
11.9 
13.1 
14.5 
16.0 
17.6 
19.2 
21 
23 
25 
27 
29 
31 
34 
36 
39 



300 
R. P. M. 



10.1 

11.4 

12.8 

14.4 

16.1 

17.8 

19.7 

22 

24 

26 

29 

31 

34 

37 

40 

43 

47 

50 

54 

58 



POWER TRANSMISSION 



13 



Dia. of Shaft 



Horse Power 



100 
R. P. M. 



200 
R. P. M. 



300 
R. P. M. 



2M- 

2% 
3... 



21 
22 
24 
25 

27 



41 
44 
48 
51 
54 



62 

67 

72 
76 
81 



To illustrate the use of the above table, let us assume it is 
desired to know the H. P. transmitted by a 2" cold-rolled steel 
shaft running at> 200 R. P. M. as a prime mover. By running the 
finger down the 200 column to a point opposite the figure 2 in the 
dia. column we find 16 as the H. P. given. Similarily, if it is de- 
sired to know the proper size of cold-rolled steel shafting to run 
at 300 R. P. M. as a prime mover to dehver 25 H. P., we run the 
finger down the 300 column in search of figure 25 and find that the 
nearest figure would be 24 or 26 and we choose the latter to be 
fafe and find that the figure in the dia. column opposite is 2]^", the 
dia. required. Or, let us find the H. P. for cold-rolled steel shafting 
2^1/ in dia. to run 250 R. P. M. as a prime mover. Reference 
to the table will show that no 250 column is given but, in 
the 200 column for this dia. we find 21 as the horse-power and 
in the 300 column we find 31 as the horse-power and as 250 
R. P. M. is half way between 200 and 300 R. P. M. we accept 
the figure 26, which is half way between 21 and 31, as the H. P. 
required. 

The above table is accurate only for cold rolled steel shafting. In 
order to make it of more use the following rules are given. 

1 — For H. P. transmitted by turned steel shafts as prime 
movers, multiply the figures in the table above that represent 
H. P. by 0.8. 

2 — For shafts as second movers or line shafts with bearings 8 ft. 
apart, multiply by 1.43 for cold-rolled and by 1.11 for turned 
steel shafts to get the H. P. safely transmitted. 



14 SCHOOL SHOP INSTALLATION 

3 — For simply transmitting power (short counter-shafts, etc.) 
with bearings 8 ft. apart or less, multiply by 2.0 for cold-rolled 
and by 2.5 for turned steel shafting. 

As an example of the above let us assume that we wish to know 
the H. P. that is safely transmitted by a 23^" turned steel line shaft 
with bearings 8 ft. apart running at 200 R. P. M. Referring to the 
table, we run the finger down the 200 column of figures to the 
number in this column opposite 2}/^' dia. and we find that 31 is 
the horse-power given. This 31 H. P. represents the H. P. per- 
missible with cold rolled steel shafting as a prime mover but as we 
wish to know what H. P. is advisable with turned steel shafting as 
a line shaft we refer to rule 2 above. This rule reads to multiply 
the 31 H. P., gained from the table, by 1.11 which gives us 31x1.11 
= 34 H. P. Rules 1 and 3 can be used similarly. 

7. Position of Shafting. — Shafting may be fastened to the 
wall, to the ceiling or to the floor. The greatest economy of space 
is obtained in most cases by fastening it to the ceiling. When 
fastened to the wall or floor the arrangement of the belts and 
pulleys makes them inconvenient and dangerous if an attempt is 
made to use the floor space close to them. Shafting on the floor 
should be well guarded by fences or railings. The number of 
machines that can be driven from shafting elsewhere than on the 
ceiling is limited. The belts from lathes, for instance, must run 
to pulleys above the lathes. 

The distance apart of shafts, counter-shafts, and connected 
pulleys will depend upon (1) physical limitations and those of 
convenience, and (2) width of the belt to be used and the corre- 
sponding work expected of it. The necessary arrangement of the 
shafting and rnachinery may be such as to make other considera- 
tions quite dependent upon their arrangement but, if possible, 
the distance between the pulleys should be such as to allow of a 
gentle sag to the belt when in motion. This allows a belt to have 
better contact with the pulleys and requires less tension on the 
belt for the same amount of horse-power. Increased tension means 
increased strains in the belt and added wear and friction in the 



POWER TRANSMISSION 15 

bearings. About 2" of sag in narrow belts and from 3 to 4" in wide 
belts is sufificient. 

Where it can be avoided, connected pulleys should not be placed 
one directly above the other for then only a minimum contact 
with the belt is obtained, and more tension in the belt is required 
to deliver a certain amount of horse-power than if the pulleys con- 
nected more nearly horizontal. 

8. Hangers. — There are three common types of hangers em- 
ployed for the suspension of shafting, viz. : drop, post and wall ex- 
tension hangers. Each type varies in that some are rigid and not 
easily adjusted while others have varying methods of adjustment. 

The best types of drop hangers are those which have screw 
adjustments. Two screws adjust the up and down movement and 
two others adjust the lateral or side movement. These screws 
aid materially in securing a quick and accurate aligning of the 
shafts. Other types have screws for adjusting the vertical move- 
ment of the bearing only. A refinement of the former type is the 
substituting of a roller bearing which minimizes the friction and 
wear, is light, being made of pressed steel, and in the end pays for 
the added cost. This type, as well as some types without roller 
bearings, has an advantage in having bearings of different sizes 
interchangeable in the same hanger. 

The rigid types are more difficult to adjust and require the 
wedging or moving of the whole hanger in order to change the 
alignment. The drop hangers are intended for over-head use but 
can be used on the floor. The size of a hanger depends upon the 
duty to be imposed upon it and the size of the pulleys to be used 
on the shaft. Hangers vary in size according to the distance from 
the wall, or other support, to the center of the shaft opening. 

Wall hangers are for use on side walls although they can be 
used on posts. Their design is such that they are more rigid for 
side wall use than are drop hangers. A post hanger has much less 
distance from its base to the center of the shaft opening than a 
wall hanger because it is designed for use on posts where, ordinarily, 
no allowance need be made for pulley clearance. The matter of 



16 SCHOOL SHOP INSTALLATION 

adjustment, as explained in connection with drop hangers, also 
applies to wall and post hangers. 

Hangers should be of sufficient size to allow of plenty of free- 
dom for pulleys and belts, and the possibility of adding larger 
pulleys in the future should be considered. The distance apart 
that hangers should be placed depends upon the size of the shaft- 
ing, the number and sizes of pulleys the latter will carry, the amount 
of power to be dehvered or taken at certain points in the shaft, 
and the direction and pull of the belting. In the best practice 
and in order to obtain stiffness, hangers are placed each side of the 
receiving pulley, the pulley connecting with the secondary shafting 
and any pulleys upon which there are extra demands, like those to 
which a large planer is connected. Where convenient, belting 
should be distributed alternately to one side and then to the oppo- 
site side of a shaft in order to balance the pulhng forces as much as 
possible and save wear on the bearings. It is evident that if suc- 
cessive belts run to one side of the shafting with none running to 
the opposite side there will be excessive wear upon the bearings. 
The same principle would hold in regard to belting from above and 
below the shaft. 

The following table and formulas can be used as a guide in 
determining the distance apart of hangers. This table is good for 
normal conditions only as regards number, size, and weight of 
pulleys, pull of belts, work to be done, etc. Where the work to be 
done is excessive the hangers should be closer together than is 
indicated in the table. 

Kimball and Barr say that the allowable distance between 
hangers can be determined by the formula L = 7V d? for shafting 
without pulleys, and L = bT^ for a shaft carrying the usual 
amount of pulleys. L = the distance in feet, d = the diameter of the 
shaft in inches. As an example, find the distance apart of bearings 
for a 2" shaft carrying the usual amount of pulleys. Substitut- 
ing 2 for d in the second formula, we get L = 5'v 2 X2 = 7.93 ft. 
or practically 8 ft. apart. The larger the shaft the farther apart 
may the bearings be. 



POWER TRANSMISSION 17 

TABLE OF DISTANCES OF HANGERS APART 

Center to Center — Normal Conditions 
Diameter Distance be- 

of Shaft tween Hangers 

Inches Feet Inches 

1 5 

\]4 5 9 

\V2 6 6 

1% 7 3 

2 8 

2\i 8 6 

2}^ 9 3 

2% 9 9 

3 10 3 

31^ 11 

33^ 11 6 

9. First Alignment; Hangers and Shafting. — The first align- 
ment of shafting, preparatory to locating the hangers, may be 
obtained in several ways. In the first way, having marked for the 
two extremities of the proposed fine, the transit is placed directly 
under the point where one extremity is to be. A plumb line can 
be used for this determination. The transit is then accurately 
leveled and sighted at the point at the other extremity. Then, if 
the movement of the transit in the horizontal plane is prevented 
by adjustments, as many intervening points may be sighted and 
marked as is wished. A very similar procedure is followed when 
aligning for hangers on the side wall, only in this case the vertical 
movement of the transit is prevented so that it will always sight 
in a level plane. Targets are used in connection with the transit 
in this method of aHgning. 

In using a stretched fine method, two points, near the extrem- 
ities of the position that the shaft is to take, must be known. A 
line is stretched tight exactly thru these points, and by it can be 
determined any intervening points. A cord is not desirable as it 
can not be stretched as taut as it should be. A piano wire is very 
good for this purpose. 



18 SCHOOL SHOP INSTALLATION 

In a new shop, alignment may be effected by nailing blocks on 
the floor directly under where the shaft is to be. By using a straight 
edge and level, and planing the blocks when desired, they can be 
made exactly level. A chalk line should then be stretched across 
the blocks and a mark on them made. Over these marks and by 
means of a plumb line, a center point for each hanger can be ob- 
tained. By using a template having a center hole and bolt holes 
for the hanger, and putting this center hole on the point located 
by the plumb line, the points for the hanger bolt holes can be 
located. The shafting can be located as to distance above these 
leveling blocks by using a stick cut to a length equal to the distance 
from the blocks to the position that the bottom of the shafting 
should have. 

By using a stick of the desired length, counter-shafts on the 
ceiling may also be located parallel to the hne shaft and at a certain 
distance from it. Counter-shafts on the floor may be located by 
dropping a plumb line at two points from the main shaft, chalking 
a I me thru these points and making the counter-shaft parallel to 
this line. 

10. Fastening Hangers. — Where it is known that a building, 
which is to be built of concrete, must support shafting hangers, pro- 
vision should be made in the plans for the fastening ot the hangers. 
A more satisfactory job of installation can be performed if materials 
are imbedded in the green concrete when the building is being 
constructed. Where it is necessary to put up shafting on old 
concrete, the hangers must be bolted to the concrete. Expansion 
bolts are useful for this purpose. Shaft hangers on wooden build- 
ings may be fastened by lag screws or bolts. 

11. Second Alignment. — The second alignment of shafting in 
the vertical plane can be performed by tightly stretching piano 
wire horizontally opposite the center of the extremities of the shaft 
and equidistant from the shaft at each end. The bearings can then 
be so adjusted that, by measurement, it is found that the shaft is 
exactly parallel to the wire thruout its length. 

To align the shaft in the horizontal plane or make it level, 



POWER TRANSMISSION 



19 



hangers or hooks, similar to those shown in C, Fig. 1 are hung over 
the shaft A to support on their lower ends a straight edge B. Nuts 
E on the hanger raise or lower the straight edge to make it parallel 
to the shaft. The gauge F will aid in making the distance between 
each end of the straight edge and the shaft equal. The straight edge 
should be made of pine and should be at least 1" thick. The upper 
edge should be planed perfectly straight. The level D is put on 
this edge and from it one can tell when the boxes have been so 





Fig. 1 

adjusted that the shaft is level. This is an efficient and simple 
method. 

12. Set Collars. — Every shaft should have two set collars to 
limit the end play. They should never be placed, however, so as 
to allow of no end play, for any shaft will run better and the bear- 
ings wear longer if a small amount of end play is allowed. The 
collars are sometimes placed, one at each end of the shaft. This 
plan is not so good as that of putting them one at each side of a 
centrally located bearing, as, in the first case, variations in temper- 
ature, especially in a long shaft, will change the amount of end 
play and either permit of too much play or so Httle play as to cause 
undue friction. " The second method will cause neither of these 
troubles. 



20 



SCHOOL SHOP INSTALLATION 



A 



E 



L=U 



13. Aligning Pulleys.— In order to have belts run true on pulleys 
of parallel shafting, it is necessary to have the two shafts in line 
vertically and horizontally. They can be placed in parallel hori- 
zontal planes by getting each one level. If they are not to be very 
far apart, they can be located in parallel vertical planes by using 
a stick, cut to the desired length, as a means for making them 
equidistant from one another at all points. 

Where shafts are a considerable distance 
apart their alignment in parallel vertical 
planes may be tested by dropping plumb 
Z2> hues to the floor, from which points on the 
floor may be located and a chalk mark 
struck. These marks will be directly under 
the shaft and by careful measurement with 
13 a steel tape one can determine whether they 
are the same distance apart at all points 
or not. If they are not far out of Hne they 
can be adjusted by means of the bolts in the 
hanger. 

Not only must the shafts be aligned properly but it is also 
necessary that the centres of the pulleys be in line. Referring to 
Fig. 2 and assuming that the shafts are in hne, the pulley F is 
fixed, and it is desired to bring pulley E in line with pulley F, a 
string A-B is drawn taut across the puUeys close to the shaft and 
at a distance of Y2 or so from pulley F. The pulley E is then 
moved until the distances a, h, c, d, between the rims and the 
string are all equal. In case one pulley is wider than the other, 
due allowance should be made so that the centres of the pulleys 
are fixed in hne. 

14. Pulleys. — The pulleys commonly used are of the fol- 
lowing kinds: cast-iron solid, cast-iron split, wood spht, pressed 
steel, and paper. Those types which are held in place on the 
shafts by means of keys or set-screws are not as desirable as 
those that can be clamped tight. A key weakeni a shaft and 
when it is necessary to change a pulley, it is often also necessary 



d 

B 
Fig. 2 



POWER TRANSMISSION 21 

to cut a new key-way. Pulleys with set screws do not hold as 
well as is often wished. Key-ways in cold-rolled steel shafting 
often release the tension in the surface of the shaft, putting it out 
of form. 

The cast-iron soHd pulley is the poorest type because it is not 
easily taken off or put on, is not adjustable to various sizes of 
shafting, is easily broken and requires a key or set-screw to hold it. 

Cast-iron split pulleys are better, for they are more easily taken 
off or put on and have bushings which make them adjustable to 
shafts of different sizes. They are easily broken, however. 

Wood spHt pulleys are fairly good, but they loosen rather 
easily, squeak, and are affected by atmospheric conditions. They 
have bushings of various sizes and make good belt contact. 

Paper pulleys are light, cheap, non-breakable and give good 
belt contact, but they require keys and are not adjustable to 
shafts of varying sizes. 

Pressed steel pulleys are the best and latest development. They 
are Hght, durable, fasten tightly, are easily changed, do not break 
and have interchangeable bushings. 

Pulleys on which a belt is not shifted should have a crown. 
This crown aids materially in keeping the belt in the center of the 
pulley. If it were not for this crown, arms would be necessary to 
keep the belt in place and they wear the edge of the belt. Tight 
and loose pulleys, upon which a belt is shifted, do not ordinarily 
have crowns. 

15. Placing Pulleys. — Pulleys should be placed as near bear- 
ings as possible to prevent undue deflection of the shafting and 
corresponding friction. Tightening or guide pulleys, when used, 
should be on the slack side of belt near the smaller pulley. Pulleys 
should be a ti'lfle wider than the belts to be used on them to prevent 
over-hang of the belt. 

16. Shaft Couplings. — There are several good styles of shaft 
couplings. Those which require no keys and which have no bolt 
heads or other projections to catch things and cause damage are 
preferable. 



22 SCHOOL SHOP INSTALLATION 

17. Rules for Finding Sizes and Speeds of Pulleys. — Of the 
two pulleys, the driving pulley is the one nearest the source of 
power. 

1. To Find the Size of Driving Pulley multiply the diameter of 
the driven pulley by the revolutions it should make and divide 
the product by the revolutions of the driver. 

Example: The dia. of the driven pulley is 12" and it should 
make 240 R. P. M. The R. P. M. of the driving pulley is 160. 
What should its diameter be? 

Answer: 12 X 240 = 2,880 and 2,880 divided by 160 = 18", dia. 
of the driving pulley. 

2. To Find the Size of Driven Pulley multiply the dia. of the 
driver by its R. P. M. and divide the product by the R. P. M. of 
the driven. 

Example: A driving pulley 18" in dia. makes 160 R. P. M. and 
the driven pulley should make 240 R. P. M. What should be its 
diameter? 

Answer: 18 X 160= 2,880, and 2,880 divided by 240= 12", 
dia. of the driven pulley. 

3. To Find the Number of Revolutions (R.P.M.) of Driven Pulley 
multiply the dia. of the driver by its R. P. M. and divide the 
product by the dia. of the driven. 

Example: A driver 18" in dia. makes 160 R. P. M., and the 
dia. of the driven pulley is 12". What is the R. P. M. of the 
driven? 

Answer: 18 X 160 = 2,880 and 2,880 divided by 12 = 240, the 
R. P. M. of the driven. 

4. To Find the R. P. M. of the Driving Pulley multiply the 
R. P. M. of the driven pulley by the dia. of the driven pulley and 
divide this product by the dia. of the driving pulley. 

Example: The R. P. M. of the driven are 500 and its dia. is 
6" while the dia. of the driving pulley is 15". What is the R. P. M. 
of the driving pulley? 

Answer: 500 X 6 = 3,000, and 3,000 divided by 15 = 200, the 
R. P. M. of the driving pulley. 



POWER TRANSMISSION 23 

Bibliography 



1. Kent, Mechanical Engineer's Pocket Book. 

2. Kimball and Barr, Machine Design. 

3. Halsey, Handbook for Machine Designers. 

4. Swingle, Handbook for Millwrights. 



CHAPTER II 

Motors and Currents 

18. General Considerations. — In a book of this nature it 
would not be possible to give complete information for the choice 
of the type, style or size of electric motors. This is a matter about 
which teachers should get advice from an engineer or the service 
department of motor manufacturers. However, a discussion of 
the problem is of advantage to the teacher if, by such, he sees the 
many technical points involved in properly choosing a motor, and 
realizes the advisability of consulting an authority in the solution 
of the problem as a whole. 

The conditions cf capacity and efficiency are both of import- 
ance in any motor installation. The installation of a motor having 
too large a capacity should be avoided unless an increase in the 
load is to be expected in the near future, such as additions of equip- 
ment, for the efficiency of a motor is generally at its maximum at 
its normal rated output. Too small a motor is also undesirable as 
it is unquestionably liable to be subjected to over-loads, causing 
the motor to burn out, making temporary use of the machinery 
impossible. 

19. Two Types of Work. — The school shop ordinarily offers 
two varieties of work for the motor, i. e., 

a) work which requires the motor to operate automitically 
at a practically constant speed, regardless of load changes or other 
conditions. 

b) work in which the power varies regardless of the speed, or 
where speed variations with constant torque may be desired. 

In (a) an example is found in the case of line-shaft equipments 
with a number of machines operated by the same motor, and where 
only slight variations are desired. In this case the D. C. shunt 
of slightly compounded motor or the A. C. induction motor would 

24 



MOTORS AND CURRENTS 25 

answer the purpose and the choice would depend upon the type of 
current available. 

Work, of the nature explained in (b) is found in certain types 
of individual drive machinery, such as machine or wood lathes 
where the maximum allowable turning speed varies inversely as 
the diameter of the cut. Such work is best satisfied by the use of 
D. C. shunt or slightly compounded motors, as their speed is 
readily controlled. 

20. Advantages of A. C. Motors. — 

1. Motor runs with little change of speed under a 

heavy load. 

2. The usual current in cities is A. C. 

21. Advantages of D. C. Motors. — 

1. Wider air gap, allowing more wear in the bearings 

before the motor needs repair. 

2. The possibility of variations of speeds. This is a 

decided advantage. 

22. Data Required in Determining the Choice of Motor. — The 
following points are essential for the proper choice of type and size 
of motor: 

1. Individual or group drive? 

2. If individual drive, the machine and the kind of 

work to be done on it. 

3. If the group drive, and some of the machines operate 

intermittently, give details of the work of these 
machines. 

4. Statement of insurance rules. 

5. Is variation of speed desirable? 

6. How is this variation controlled? 

7. Speed of machine, size of pulley and belt? 

8. Is belt pull at top or bottom? 

9. Will there be any combustible material near motor? 

(shavings, saw-dust, etc.) 

10. Where will motor be fastened? 

11. Voltage and type of current. 



26 SCHOOL SHOP INSTALLATION 

This list does not include all that might be necessary but gives 
one an idea of the advisability of seeking competent advice when 
choosing a motor. 

23. Planning for Motor Drive. — In arranging motor-driven 
school shop equipment the following points should be observed: 

1. To provide ample aisles and operating and stock 

space between machines. 

2. To arrange the machines so that the routing of 

work, in some order, can be effected. 

3. To locate the machines so that good Hghting con- 

ditions exist. 

4. To locate motors where they are accessible. 

5. To guard motors, shafting and belts properly and 

yet make them accessible for cleaning, oiling, re- 
pairing and adjusting. 

24. Installation of Electric Motors. — The foundation for 
electric motors must be solid, to prevent vibration. Solid masonry 
or concrete is the best material, but wood or timbsr framing can 
be used. All motors should be insulated from contact with metal. 
Great care should be taken in aligning the motor shaft with the 
driven shaft if the latter is to be connected directly to the 
motor. 

25. Care of Motors. — Only the best quality of oil and grease 
should be used on the bearings. The best quahty of lubricant is 
more economical than worn bearings. Bearings provided with 
oihng rings should have a good grade of dynamo oil, and should be 
filled to the top of the over-flow plugs. The plugs should be kept 
free, and all dirt, dust and gritty materials must be kept out of the 
bearings. Excessive belt tension, which heats the bearings, should 
be avoided. The commutator and brushes should be kept clean. 
Emery cloth is injurious to the commutator and brushes. A clean 
cloth or waste should be sufficient to remove the dirt. 

Sparking at the commutator of D. C. motors is often caused by: 
1. An over-load. Release some of the load. 



MOTORS AND CURRENTS 27 

2. Improper brush adjustment. If a brush fits the 

commutator properly, the entire face of it will be 
glazed. 

3. Improper brush contact — 

(a) Grease or dirt accumulations. 

(b) Brushes may stick in the holder and need sand- 

papering to free them. 

(c) Increased brush pressure may be needed — 

change adjustment on spring. 

Bibliography 

1. Industrial AppHcation of Motors — American Handbook 
for Electrical Engineers. 

2. Installation, Care and Repair of Electrical Motors in 
Industrial Operations, Electrical Review, 1909, Vol. 55, pp. 795, 
845, 892, 944. 

3. Selection of Direct-Current Motors for Factory Use, 
Engineering Magazine, 1911. 

4. Selection of Motors for Different Kinds of Service — F. B. 
Crocker and M. Arendt, Electrical World, Nov. 1907. 

5. Choice of Motors for Machine Tools, Kent's Mechanical 
Engineer's Pocket Book. 

6. Relative Costs of Group and Individual Drive — G. E. 
Sanford, General Electric Review, Vol. 15, p. 17. 

7. Catalogs and literature distributed by motor manufacturers. 



CHAPTER III 

Installation of Metalworking Equipment 

26. General Considerations. — In general, the installation of 
metalworking equipment requires a knowledge of the floor space 
necessary for each machine or object of equipment, the space for 
the operator to work in and the space for the machines to operate 
in. Also, the placing of the rr.achines, as regards the light for their 
operation, should be considered. Sufficient aisles should be pro- 
vided, and the machines located so as to be accessible for adjust- 
ment or repair. Safety points on machines, shafting, belts, motors, 
etc. should receive careful attention. Storage places for tools, 
raw and finished stock are necessary. The placement of machines, 
in respect to their convenience to each other, should be considered. 
Drills, for instance, are used in connection with several machines 
and operations and should be centrally located in respect to these 
machines, if possible. 

It is possible, sometimes, to economize on space by doubUng 
up on equipment, i. e., a bench, used for chipping and filing, may 
also be used for sheet-metal work, or in connection with auto re- 
pair, depending upon the arrangement of the room and the schedule 
of classes. 

Small machines should be bolted to the floor or foundation. 
Heavy machines should be grouted or wedged with shingles and 
bolted. On concrete floors, expansion bolts may be used to ad- 
vantage. 

Speeds and sizes of the pulleys will be determined from the 
specifications furnished by the manufacturers. 

27. Planer. — Daylight should come from the left of the oper- 
ator as he is at work, if possible. This would mean that the work- 
ing stroke of the planer would be away from the light. If thi3 
arrangement is not convenient, then the planer should be placed 

28 



METALWORKING EQUIPMENT 29 

so that the working stroke is parallel to the windows and the oper- 
ator faces the light. Artificial light should be about 2 ft. in front 
of the tool-post and over the center of the platen. 

There should be 4 ft. of space between the end of the table or 
platen and the wall, or other objects, after the extreme travel of 
the platen. Otherwise, the table, in running off the gear, as it 
does sometimes, might pinch a person against the wall and injure 
him most seriously. There should be at least a 4 ft. space parallel 
to the side of the planer for the operator. 




Fig. 3 

A consideration, often overlooked, is the necessity of leveling 
the bed of the planer or the ways in order to obtain the best quaUty 
of work from the machine. It should be leveled across the ways 
and lengthwise of them. To get the two ways level, put two round 
bars, of the same diameter, in the ways as shown in Fig. 3, and 
across the bars place a level. Bolster up the planer until it is level 
at this end and wedge or grout it. Level it thus at each end and 
intervening points. 

To test the ways to see if they are concaved or convexed 
lengthwise of the planer, place the bars in the ways as before, 
but in place of the level put a straight edge across the bars. In 
this case, the bars should be rather short. Similarly, at a distance 
of 2 to 4 ft. along the bed place two more bars and a straight edge. 
Across the two sfraight edges, and connecting them, lay a level. 
Fig. 4. Repeat this whole procedure by moving these tools along 



30 SCHOOL SHOP INSTALLATION 

the bed but have each space being leveled overlap the previous 
space leveled. By this means the ways can be leveled lengthwise 
and, by wedging, or grouting and fastening to the floor, the planer 
can be held level. 

28. Lathe. — It is preferable that daylight should come from 
the right as the operator is at work at the lathe, so that he casts no 
shadow on the work. Artificial light should be directly over the 
bed of the lathe near its center. Lathes, placed end to end, should 
have at least 2 ft. of space between them to allow for the opening 
of cages over the gears and for passageway. Lathes, placed back 

Level St rafghf 
^ Ways 




to back, should have a 1 ft. space between those parts of the lathes 
nearest meeting. The lathe bed should be leveled as explained for 
a planer, and the legs properly supported by shingle wedges or 
grout. The legs should be bolted to the foundation. 

29. Drill Press. — DayHght should come from the left or right. 
Artificial light should be at the height of the head to the left or 
right of the center. There should be 3 ft. of working space at the 
front and the two sides. The machine should be set so that the 
table is level as it is often necessary to set up work by the use of 
the level. 

30. Milling Machine. — There should be space on three sides 
for the operator. Light should come from the left or right if possible. 
Artificial fight should be in the front of the center of the machine 
just above the head. 



METALWORKING EQUIPMENT 



31 



31. Shaper. — Light should come from the left or right as 
operator works. Three feet of space beyond the extreme travel 
of the slide is desirable. 

32. Forge. — Double forges have an advantage in that the 
initial cost and that of operation is less, and also because there is 
an economy of space with this type. Further economy of space 
is often gained by placing them at an angle of 45 degrees with the 
imaginary line thru the center of the forges. 

Single forges should be placed about 5 ft. 4" apart on centers as 
a minimum. 




-H-26"— J 






Fig. 5 



The hood should be at the left and also the lever that controls 
the air. 

33. Anvil. — There should be from 24" to 26" of space between 
the anvil and the forge. The anvil should be turned at an angle 
of about 50 degrees and the center of the anvil should be about 
two inches to the front of the center of the forge, Fig. 5. 

There should be sheet-iron around the anvil if it is on a wooden 
floor. A wood mount for the anvil set 2 ft. in the ground or in 
concrete is good. Cement mounts or stands crumble. Iron stands 
are clumsy, in the way of the feet of the worker and have openings 
around the anvil into which tools are dropped and are bothersome 
to extract. For a grown person, the top of the anvil should be 
about 28" above the floor. 

34. Blower. — Individual blowers for each forge are advan- 
tageous for it is' then not necessary to run a big blower sufficient 
for all forges when only a few are being used. The cost of installa- 



32 SCHOOL SHOP INSTALLATION 

tion for underground blast piping is saved, the loss of power due 
to friction is minimized and the total power required is less, for, 
with a single large blower, the pressure is kept up to a certain 
maximum at all times. 

In case it seems advisable to install a blower and exhauster, a 
motor driven fan is preferable. The motor can be placed between 
the fans of the blower and exhauster, having the shaft extend each 
way into the fans. 

In planning a forge room, it would be advisable to submit, to 
the engineering department of reputable makers of forge equip- 
ment, the dimensions of the forge room, as well as the number of 
the forges to be installed and the preferred location of same. The 
engineering department will then prepare a suggestive lay-out 
showing an economical arrangement of forges, anvils, and under- 
ground ducts. 



CHAPTER IV 

Installation of Woodworking Equipment 

35. General Considerations. — No hard and fast rules can be 
given that will determine for one the exact arrangement of machin- 



1 

1 




/ 

/ 




o 


1 


— 1 
1 


















n 


1 

1 


CO 








1 


JOINTER 




1 
c/> 1 


I 
















J 


t^ 


, 




-16' 




1 
















1 

1 
1 






"""ir 




r 




00 










5URFACER 


Co 1 


1 

















J 




■ -\- 






I 










1 
1 






° 1 




U 






1 

— 17' — 


-- 


"T 


1 







1 T 1 

' 1 




/ 
/ 


1 
1 










1 





Fig. G 
33 



I6i 



34 



SCHOOL SHOP INSTALLATION 



ery. Existing conditions are varied and only points for consider- 
ation can be shown. 

One should know the approximate floor space necessary for 
different machines as well as the operating and stock spaces deemed 
essential. The floor spaces will be given by the manufacturer in 
the specifications of the machines. The operating and stock 
spaces for various machines should be approximately as shown in 



LATHE 



— } 

5 _ J 



AUI GRIMDER 



TTT 



M0RTI5ER 

-; I 

h 6' 



©- 



6'/?. 



BAfND SAW 
S 




Fig. 7 



BAND 5AW 



LA 
/ 

/ 



jAUT. GRIHDLR | 



/ 



Fig. 8 



WOODWORKING EQUIPMENT 



35 



Figs. 6 and 7. These are respectively designated by O and S. It 
might happen that an S space, allowed for one machine, might 
overlap an S space for another machine with no inconvenience. 
For instance, an arrangement like that shown in Fig. 8, where the 
stock space for the band saw overlaps that for the automatic 
grinder, would not be a serious inconvenience. 

In locating the different machines, 
it is necessary that the pulleys on the 
machines Hne up with the pulleys on 
the line or counter-shaft over which 
- the belts for the machines under con- 
sideration run. , If in Fig. 9, a wire or 
strong cord is stretched tight across 
the upper and lower rim of pulley C 
on the line-shaft close to the shaft, and 



-= 


A 
C 

D 


I 

FLOOR LlfNt^ 




Fig. 9 



Fig. 10 



the machine E is so moved as to bring the rim of the pulley D 
just to the Hne also, and pulleys C and D are plumbed with a 
plumb bob, as in Fig. 10, there will be no trouble with the belts 
running off, provided, of course, that the pulleys are properly 
hung on their respective shafts. 

The speeds at which different machines should run are given 
in the specifications by the manufacturers. Formulas for figuring 
sizes and speeds of pulleys, width of belts, etc., are given in the 
chapters on "Power Transmission" and ''Belting." 



36 



SCHOOL SHOP INSTALLATION 



36. Speeds of Various Machines. — For reference, the speeds 
of various machines are given below : 

1. Grindstone — circumferential speed of from 600 to 800 ft. 
per minute. 

2. Crosscut-saw and rip-saw — rim speed of 10,000 ft. per 
minute. 

3. Jointer— speed of cyHnder, 4,000 to 5,000 R. P. M. for large 
size, and about 5,000 R. P. M. for 6'' knives. 

4. Lathe— variations of spindle from 600 to 3,000 R. P. M. 

5. Mortiser— bit runs 3,450 R. P. M. with 10 to 35 strokes of 
the chisel per minute. Driving pulley on countershaft 
makes 1,100 to 1,200 R. P. M. 

6. Surfacer— speed of head 4,000 R. P. M. 

7. Band-saw — about 4,500 ft. per minute rim speed. 

8. Cut-off saw — 10,000 ft. per minute rim speed. 

37. Emery Wheel Speeds. — 





Diameter or Wheel 


R. P. M. FOR Surface Speed 




IN Inches 


OF 5,000 Feet per Minute 


1.. 




19,099 


2.. 




9,549 


3.. 




6,366 


4.. 




4,775 


5.. 




3,820 


6.. 




3,183 


7.. 




2,728 


8.. 




2,387 


10.. 




1,910 


12.. 




1,592 


14.. 




1,364 


16.. 




1,194 


18.. 




1,061 


20.. 




955 



WOODWORKING EQUIPMENT 37 

38. Circular Saw Speeds. — 



Size of Saw in Inches 


R. P. M. 


8. 




4,500 


10. 




3,600 


12. 




3,000 


14. 




2,585 , 


16. 




2,222 


18. 




2,000 


20. 




1,800 



39. Horse-Power Required for Woodworking Machines.^ 

This can be stated only approximately due to varying conditions 
of work to which machines are subjected, such as whether wood is 
soft or hard, 1" or 3" thick, whether the machines are kept in good 
condition or not, etc. The general requirements are as follows: 

1. Cut-off saws require 2 to 4 horse-power. 

2. Crosscut and rip saws require 3 to 5 H. P. 

3. Surfacers, 18"— 5 to 7 H. P.; 24"— 7 to 10 H. P. 

4. Jointers, Q"—l}4 H. P.; 8"— 2 to 3 H. P.; 16"— 3 to 4 H. P. 
and 20"— 4 to 5 H. P. 

5. Hollow chisel mortisers, 13^ H. P. 

6. Lathe, >^ H. P. each. 

7. Automatic Grinder, 2 to 3 H. P. 

40. Other Factors to Consider. — Woodworking machines do 
not require as careful leveling as do most metalworking machines. 
However, they should be approximately level, and, in the case of 
the lighter machines, should be bolted to the floor. 

The crosscut- and rip-saws should have light from the front, if 
possible; mortisers from the left or right and lathes from the front 
or right side as the operator faces the lathe. The light for the 
surfacer, jointer, sander or band-saw is not so particular a point 
as for the other 'machines, provided there is good light in the room 
as a whole. 



38 SCHOOL SHOP INSTALLATION 

Some attention might well be given to the routing of stock when 
planning for the placement of machines. From the stock room or 
cut-off saw, the majority of the stock goes to the rip-saw, jointer 
and surfacer. This would indicate that these machines might 
well be placed convenient to each other and to the stock room. 



PART TWO — MAINTENANCE 

CHAPTER V 

Fitting Edge Tools 

41. Plane Irons are not all fitted alike. The usual equipment 
consists of a jack-plane for making heavy first cuts, a smooth-plane 
for making finishing cuts and for use on broad surfaces, and a fore- 
plane or a jointer for making a true, straight edge. 

Because of the depth of cut demanded of a jack-plane and 
because of the fact that a heavy shaving, the full width of the 
blade or iron, would cause trouble by choking in the throat, the 
blade is usually ground a trifle rounded, similar to Fig. 11. This 




Fig. 11 Fig. 12 

condition is obtained by bringing shghtly more pressure, first on 
one corner and then the other, than on the center of the iron, when 
grinding it. 

The smooth-plane irons are ground perfectly straight across 
and then about two strokes are given each corner to produce the 
effect shown in Fig. 12. If the corners are left square, the different 
cuts, on a broad surface, would be shown by shoulders or steps. 
The rounded corners cause the cuts to blend unnoticeably with 
the rest of the surface. 

The jointer iron, because of its duty in forming a true flat plane 
surface, is ground straight across the edge and the corners are left 
square. 

The angle of the bevel. Fig. 13, should be about 20 degrees, or 

39 



40 SCHOOL SHOP MAINTENANCE 

SO that the bevel measures i%" to 3^" long on each style of plane. 
Too long a bevel will cause chattering and weaken the edge so that 
it will more easily chip. Hard wood requires less bevel than soft. 
In grinding a plane-iron, the cap-iron, which is the piece that 
is clamped on the cutting iron or blade, should be loosened and 

^___^ shd back as far as the screw will permit 

J * and then fastened again. This will serve 

as a handle and also make a quicker ad- 



^. 



^0"* justment than if it were taken off entirely. 
^' '\ The proper way of applying an iron to an 

emery wheel or grindstone is shown by Fig. 14. It should be 
firmly grasped with the right hand and the fingers of the left 
hand laid across it near the cutting edge. It should be laid on the 
stone similar to a, Fig. 14, and then raised with the right hand 
until the desired angle of contact is made. This is shown by 
b, Fig. 14. If the bevel already on the tool is correct, this position 
can be determined easily by watching the cutting edge to see when 
it first comes in contact with the stone. No tool should be held 
in one place on the stone, but should be moved slowly back and 
forth across the stone to keep the wear even on both the stone and 
tool. The angle of contact with the stone, however, should be 
kept as constant as is possible. Otherwise, the effect shown in 
Fig. 15 will result, making a stubby, poor cutting edge. Because 
of the difficulty in holding 
the tool at the same angle, 
a clamp or jig is often used. 
This has a roller on the end, 
opposite that on which the 
iron is clamped, that rests 
on the stone. This clamp 

permits of any ordinary angle of bevel and can also be used for 
chisels. In grinding on an emery wheel, great care should be 
taken not to burn or draw the temper of the tool. This can be 
told by a blue color appearing at the cutting edge. A tool that 
has been burned will not keep an edge as long as it should. Grind 




FITTING EDGE TOOLS 41 

the irons until a feather edge is turned over on the back of the 
tool and then stop. Further grinding makes them no sharper and 
only wears away the tool. 

Having ground the irons, the next process is that of whetting. 
This is done on an oilstone, usually of a size about 6" x 2" x 1". 
The tool is grasped by the right hand and the fingers of the left 
^_____^____^ are laid across it near the cutting edge. It is 
) ^ applied to the stone like a, Fig. 16, and then is 

Y\„ l^ tipped up to the position of h. It will be noted 

that this position is not one where the bevel is 
fiat on the stone, but where it is raised from the stone slightly at 
the heel. Were the bevel laid flat on the stone, the time required 
to get a fine cutting edge would be much greater than by the former 
method, and the efficiency of the cutting edge would not be in- 
creased. Care should be taken, however, to make this angle only 
sHght and to keep it constant. If a tool is held properly in grinding 
the form of the bevel will be a concave plane of the same curvature 
as the wheel upon which it is being ground. When appUed to the 
flat surface of an oilstone, the tool will touch only at the toe and 
heel, and the time necessary to whet it will be short, even with the 
bevel fiat on the stone. It is hard, however, especially for an 
unskilled workman, to get a concave bevel on a tool, and for that 
reason it is advisable to u 

raise the tool as ex- 
plained above. 

For the beginner at 
least, the motion of the f 
iron on the oilstone ) 
should be circular as in 
Fig. 17. This presents 
the cutting edge more evenly to the stone and keeps the stone in bet- 
ter form. One should keep changing the whetting area on the stone 
from time to time, also, so that it dojs not become hollow in any one 
place. Some of the best mechanics give a longitudinal stroke the full 
length of the stone in whetting, but it is hard for the beginner to do 




Fig. IG 




42 SCHOOL SHOP MAINTENANCE 

this and keep the bevel correct. Whetting should continue until a 
slight feather or wire edge can be felt turned over on the back 
of the iron, extending clear across the cutting edge. To remove 
this, lay the tool flat down on the oilstone with the bevel up and 
give a few light strokes in a circular motion. If the feather edge 

is not removed entirely by this, 
hold the tool upright and draw it 
crosswise of a piece of wood, 
making a cut like that of a 
knife. One such cut should re- 
move the ragged edge. In re- 
placing the cap-iron, it should 

be clamped about \i{' from the 
Fig. 17 • ^ e -i- 1 

cuttmg edge tor ordmary work, 

and closer for cross-grained hard wood. 

42. Chisels are ground and whetted exactly as are plane irons, 
with the exception of the angle of the bevel which should be from 
20° to 25° for paring chisels and about 30° for mortising or for 
heavy work on hard wood. 

43. Turning Tools. — The roughing gouge should be so ground 
that, on looking down the cutting edge, as it is held on the rest 
for cylindrical cutting, it will have the appearance of a semi-circle. 
To obtain this the angle a, Fig. 18, should be about 30°. It is held 
on the grindstone and oilstone as ex- _ . _^ 
plained for plane-irons, except that it is 1 ^ /»•'. \^ ' 
rolled with the right hand from left to ^ -' 

right to give the cylindrical bevel. 

The small gouge is ground hke the < "^^ 

roughing gouge, but has the corners of the 
cutting edge ground farther back as in B, 

Fig. 18, to give a better cutting edge on the side where it is so much 
used. After a gouge has been ground and whetted on the bevel, it is 
necessary to remove the wire edge. As this cannot be done by 
laying it fiat on an oilstone, a slip-stone is employed. The curve 
of the stone nearest matching that of the concave surface of the 



FITTING EDGE TOOLS 43 

gouge is placed flat against this surface and moved back and forth 
over the wire edge. Some prefer to strop the bevel of wood- 
cutting tools on a strip of leather glued to wood. This is seldom 
done by the mechanic. 

The skew chisels are so ground that the angle of the cutting 
edge with the length of the tool is between 45° and 60°, varying 



rr^- — 



\ V// W45" 

Fig. 19 

with the wood and the nature of the work. See a, Fig. 19. The 
angle between the bevels in h, Fig. 19, should be about 25°. The 
skew chisels are ground like other beveled tools, described above, and 
are whetted on each bevel. It is important to keep each bevel a per- 
fect plane surface and, for that reason, the bevel is laid flat on the 
oilstone in whetting and is not raised as was the plane-iron in Fig. 16. 

Scraping tools are ground so that the bevel makes an angle of 
approximately 45° with the length of the tool 
as in Fig. 20. /^ ^^ 

The parting tool, Fig. 21, has an angle of ^ 

about 50° between the beveled edges. 



> 



44. The Draw-knife is hard to hold, in ^r\ ^ ^ 
grinding, because of the handles, but should ^. ^i 

be held on the stone as explained for plane- 
irons and chisels. The whetting can be done very handily by 
holding the draw-knife, back down, on the bench with the beveled 
side next to you. It is held there by the left hand while the 
right grasps tlie oilstone and appUes it to the beveled edge as 
shown in Fig. 22. 



44 



SCHOOL SHOP MAINTENANCE 



45. Spokeshave Blades, being so short, are inconvenient to 
handle and a holder Hke that in Fig. 23 is handy. Dotted Hnes 
represent the blade in place for sharpening. It is ground and 
whetted like other beveled tools. 




ii 




.-j: 



Fig. 23 



Fig. 22 



46. The Outside Gouge is given a rotary motion in grinding 
as is the turning gouge, but unHke the latter it has a square end 
rather than a semi-circular one, when viewed at right angles to its 
length. The slip-stone must be used to remove the wire edge in 
the same manner as for the turning gouge. 

47. The Inside Gouge, so named because the bevel is on the 
the inside curve, cannot be ground on an ordinary emery wheel or 
grindstone. A device that works satisfactorily can be made on a 
wood lathe and similar in shape to Fig. 24. The small tapered 
end should fit the tapered opening for 

the live center. After it is turned smooth 
from some fine grained wood such as 
maple, it is coated with a thin coat of jr^g 24 

glue and dipped in fiower-of-emery and 

allowed to take up all the emery possible. After thoroly dry- 
ing, it is again dipped. This is repeated until three or four coats 
of the powdered emery are on it. The cons shaps allows for the 
grinding of different sizes of gouges. Inside gouges are whetted 
with a slip-stone on the bevel after being ground and a slip- 



FITTING EDGE TOOLS 45 

stone is rubbed flat on the outside of the gouge to remove the 
wire edge. 

48. Cabinet Scrapers do their work by means of a turned-over 
corner or arris. The scraper is fastened in a vise and filed flat, 
crosswise of the edge, and sUghtly rounding lengthwise, so that 
the corners will not dig. It is then draw-filed as in Fig. 25, with 
one hand grasping the end of the file and the other the handle, 
causing the file to move in the direction indicated by the arrows. 
The edge is then whetted keen on an oilstone as shown in Fig. 26, 




U ^ Fig. 2G 

Fig. 25 

and the wire edge, from grinding, is removed by whetting shghtly 
the sides close to the filed edge. The scraper should He flat on 
its side in this operation. It should now have a square-cornered 
edge free from roughness. The wire edge desired is obtained by 
rubbing a burnisher over the corner as shown in Fig. 27. The 
scraper is held firmly on the bench with the edge being sharpened 
perpendicular to the bench. The burnisher should be held with 
the point down, making a right angle with the scraper, like a, Fig. 
28, at first, an angle like that at b next, and finishing with the angle 
at c. This angle should be difi'erent from the first by not more 
than 15°. Turning the edge too far causes it not to ''bite" or 
take hold of the wood as it should. When the edge has been 
turned too far, it can be raised by running the point of the burnisher 
along under the turned edge. A burnisher must be hard enough 
not to be scralched by the scraper. A good one can be made by 
grinding a round file smooth and sharpening the end. A scraper 



46 



SCHOOL SHOP MAINTENANCE 



need not be filed every time it fails to cut well, but should have 
more of the edge turned. 

49. Planer and Jointer Knives should be ground on an auto- 
matic grinder, where possible, as the cutting edges should be 
straight and this condition is difficult to obtain by holding them 




Fig. 27 



Fig. 28 



by hand against an ordinary emery wheel or grindstone. The 
angle of the bevel with the side of the blade should be about 35°. 
In using an automatic grinder, care should be taken that the water 
is turned on to avoid burning the edge. After grinding, the bevel 
is whetted on an oilstone as explained for the plane-irons and 
chisels in previous paragraphs. Recently, grinding devices for use 
on the jointer and surfacer without removing the knives have 
been perfected. This method allows of such a fine adjustment of 
the knives as not to be compared to the older methods of sharpening 
and setting. 



CHAPTER VI 

Fitting Saws 

50. Hand Rip-saw. — The purpose of this section is to give the 
procedure for keeping in order the various saws ordinarily found 
in the school shop where the number and variety is not such as to 
require the services of special saw-fitting machinery. 

The beginner who is trying to learn to fit saws properly should 
start with a rather coarse- toothed, hand rip-saw having about four 



qO . <^o. 



Ld.rd.dM 



Fig. 29 




Fig, 30 



or five points to the inch; not an old one with uneven and poorly 
formed teeth, but one having properly shaped teeth. It is no little 
trick to fit a saw properly and the learner should have correctly 
formed teeth to work on first, his aim being to maintain this form 
as he acquires skill in the handhng of his file. Perhaps a still 
better way is to give the beginner a strip of soft steel about ^e" 
thick, 1" wide and 6" long and show him the proper lay-out for a 
rip-saw tooth of any number of points to the inch, for the form is 
the same regardless of the number of points to the inch. Have 
him then lay out on the edge of the strip teeth with points 34" 
apart, and corresponding in form to the diagram. Fig. 29, the 
arrow of which indicates the direction of the cutting stroke. 
Notice that the front of the tooth is at right angles to a hne run- 
ning thru the joints of the teeth, and that the angle, between 
the back and front edges of a tooth, is 60°, and also that the tooth 

47 



h 



48 SCHOOL SHOP MAINTENANCE 

is made by filing square across the blade so that there is no bevel 

or fleam, as in the crossscut-saw illustrated in Fig. 30. In laying 

out the teeth, use a bevel, try-square and scribe, and make the 

marks strong enough to be seen plainly. It should not be necessary 

to lay them out on both sides of the strip. Place the strips in the 

vise, as low as possible and still have clearance 

for the file. If no saw clamp is at hand, a 

very serviceable one can be made of two 

strips of %" hard wood, about 2" wide, which 

can be clamped close to the teeth in an ordi- 

■ ' ■■'■ nary bench or machinist's vise. The outside 

edges, at the top of the strips, should be 

beveled to allow clearance for the file. 

» . For fihng such large teeth, a shm taper file 

Jil. about 7" long should be used. It should have 

U a handle on it. With the handle in the right 

p^g 3j hand and the left holding the tip of the file, 

assume such a position that the file moves in 

a direction perpendicular to the side of the strip and at right 

angles to a line lengthwise of it thru the points of the teeth, Fig. 31. 

A file is made to cut on the pushing stroke only. It should be 

slightly freed from contact with the teeth on the return stroke. 

With a number of firm strokes, file out the metal between the 

teeth just to the scratch mark. 

The first operation, in fitting a saw, is to joint it if necessary. 
Then it is set and after that filed. Of course the ordinary pro- 
cedure could not be followed in this exercise. When the learner 
has carefully filed the teeth the full length of the strip, he has a 
fair idea of how the teeth should appear and, furthermore, he has 
acquired some skill in manipulating the file. 

The next step for the learner is to try to get this same form in 
the teeth of an actual saw. First, sight lengthwise of the saw at 
the teeth to see if they are all in fine, and if the line is a shghtly 
crowning one, with the middle portion about }/s" higher than at 
the ends. If the teeth are not even or the line is not crowned 



FITTING SAWS 49 

properly, the high ones must be filed until all are in line. This 
process is called jointing. For this purpose a 10" flat file should 
be used. With the saw fastened in a clamp, the file is laid flat on 
the points of the teeth and, with the fingers lightly rubbing the 
sides of the saw to keep the file from rolling sideways, it is pushed 
forward over the teeth. This is repeated in places where needed 
until the shortest tooth is just tipped or flattened on the top and 
the crown is perfect. As it is quite difficult for a beginner to hold the 
file exactly horizontal at all times, it is desirable to use a jointer. 
There are several commercial styles on the market, and one can 
be made like that shown in Fig. 32. Notice the clearance made for 
the teeth in the block close to the file. Care should be taken that 
the file is set in the block at right angles to the face of the latter. 

The next operation, which is setting, means the bending of 
every alternate tooth sHghtly to one side and the remaining teeth 
to the opposite side of the saw, the purpose being to cause the teeth 
to cut a groove wide enough so that the blade of the saw will pass 
thru without being pinched by the wood. A common fault is 
that of putting too much set in the teeth, thus causing them to 
break. Teeth should always be set to the same side as 
they were previously. Also, all of the bend or set should >-s-H 
be in the upper half of the teeth and not in the base, else rrrUn 
they are liable to break. The teeth should be set only 
enough to allow freedom of the blade in passing thru the 
groove made by teeth. The least set that is possible, and 
yet have a free saw, the better. There are a number of 
ways of setting teeth. One method is to bend them 
with a tap of a hammer over a stake or small anvil made Fig. 32 
for the purpose and held in a vise. Another method is 
that of swage setting where a swage is driven on the points of 
the teeth causing the points to spread or flare. In this case, all 
are swaged aUke and not bent to the side as in setting. 

The more common method is that of using the spring saw set. 
It is not feasible to describe the various styles, but most of them 
have a beveled disc or a sliding bar with a bevel. These pieces 




50 SCHOOL SHOP MAINTENANCE 

are so adjusted that the bend will come in the right place in the 
tooth according to the size being set. Some sets have numbers 
on the discs corresponding to the points per inch. There is also 
an adjusting screw that presses against the side of the saw and 
allows variation in the amount the tooth is bent to the side. The 
beveled piece simply determines the distance from the point that 
the tooth is bent. For ordinary dry woods, 1-100" bend to each 
side of the saw should be sufficient. Soft or damp 
woods require more set. Fig. 33 illustrates the 
effect of setting the teeth of a saw. In this sketch, 
the set is exaggerated for sake of illustration. Swage 
set is shown by a\ spring set by b. Every alternate 
tooth is set to one side of the saw; the saw is then reversed and 
the remaining teeth are set to the opposite side. 

The saw having been properly set, the next step is to file it. 
As in setting, every alternate tooth should be worked from one side 
and the remaining teeth from the opposite side. The bulk of the 
fihng should be done on the front edge of the teeth and on those 
teeth that point away from the operator, in order to avoid chatter- 
ing of the saw, with injury resulting to both the saw and file. File 
each tooth nearly, but not quite, to a point. They will be brought 
to a point later, when filing the remaining teeth from the opposite 
side. Some call the fitting completed when the teeth are all filed 
to a point. Others prefer to side-dress the saw. This consists in 
laying the saw flat on the table or bench and rubbing an oilstone 
or fine file lightly over the sides of the teeth to remove the burr 
left by the file. It is certain that a smoother cut is made by a side- 
dressed saw. 

The rip-saw is used lengthwise of a board and the action of its 
teeth are like a number of tiny chisels, each chipping a portion frorn 
the end of the fibre of wood. The crosscut-saw is used to cut 
across the fibre of the wood and its action is different. Instead of 
cutting off ends of fibres, it severs them at each side of the saw. 
One set of teeth cuts them on one side and the opposite set on the 
other side. For this reason, the teeth are brought to a sharp 



FITTING SAWS 51 

edge by filing a fleam or bevel on them. This is shown in a, 
Fig. 34. These bevels are filed on the inside edges of each tooth. 
The bevel of the front edge of the tooth should make an angle of 
about 45 degrees with the plane of the saw blade. The angle of 
the bevel in back varies with the nature of the work to be done. 
Fig. 34, a, shows a tooth of a 53^-point hand-saw for cutting 
soft wood. The bevel on the front is the same as that on the 
back. In b is shown the tooth of a 7-point saw, for medium hard 
wood, with less fleam on the back, while c shows a 10-point tooth 
for hard wood. There is no bevel on the back. In general, it can 
be said that the harder the wood the smaller the tooth and the 
less the bevel on the back of the tooth. Pitch is a term used quite 
ambiguously in connection with saws. In Figs. 35 and 3(3, this 
is represented by the difference between angles a and a respectively. 
In Fig. 35 the angles a and b are the same and the tooth is said to 
have no pitch. In Fig. 36 the point of the tooth has been pitched 
ahead 6 degrees from its position in Fig. 35 where the front edge 
makes an angle of 60 degrees with the line thru the teeth. This 
angle varies according to the work to be done, hard woods requiring 
less pitch than soft. 

51. Hand Crosscut-Saw. — The hand crosscut-saw is jointed 

and set as was the rip-saw, but it ^ 

is not filed in the same manner as y^. N /h. h /K h 
the rip-saw. It will be remem- ^ Y "" "^^ "">^ \'l 
bered that in filing the latter, the pj ^^ 

file was held horizontally and at 

right angles to the length of the saw or, in other words, square 
across the saw. For the crosscut-saw, the file should be so placed 
that it makes an angle of approximately 45 degrees with a line 
thru the teeth and at the same time should be parallel to the per- 
pendicular to the side of the saw, or horizontal. In making the 
above angle of 45 degrees, the handle of the file should swing 
towards the handle of the saw so that the file is pushed towards 
the small end 61 the saw and works on the front edge of those 
teeth which point away from the operator. As in the case of the 



52 SCHOOL SHOP MAINTENANCE 

rip-saw, every alternate tooth is filed from one side; then the saw 
is reversed in the clamp, and the remaining teeth are filed from the 
opposite side of the blade. The bulk of the filing should be done 
on the front edge of the teeth and on those teeth which point 
away from the operator, in order to avoid chattering. For 8, 7, 6 
and 5-point saws use a 6'' slim taper, three-cornered file, and for 
9 to 12-point saws use a 5" slim taper file. 



Fig. 35 Fig. 36 

A circle, turning or web saw is usually filed like a rip-saw. 

52. Key-hole Saw. — A key-hole saw is filed in a manner which 
is about half rip and half crosscut. That is, the tooth is pitched 
more than a crosscut, but not as much as a rip-saw tooth. The 
front of each tooth should make an angle of about 70 degrees with 
the line thru the points. The bevel or fleam is not so acute as that 
of a crosscut-saw, yet the tooth is not square in front like a rip-saw. 

53. Mitre- and Back-Saws. — These saws have crosscut teeth 
but, because of the fineness of the teeth, require much care. A 
cant, safe-back file should be used. 

54. Band-Saws. — Band-saws have a rip-saw tooth, the proper 
shape of which is shown in Fig. 37. If fitted by hand, they should 
receive the same treatment as a hand rip-saw, but it is a long task. 
There are a number of good band-saw fitting machines on the 
market that file and set very quickly, filing a saw in from ten to 
fifteen minutes with Httle attention after the first adjustment is 
made and the machine started. They are not difficult to learn 
to operate. The principle on which they work is the same, tho 
the construction of the machines varies considerably. The saw 
runs over pulleys and passes thru a guide on the machine. It is 
moved thru the guide to receive the stroke of the file by a plunger 



r>vr^--j---.j^^ 



FITTING SAWS 53 

finger, usually working on the tooth adjacent to the one being 
filed. An ordinary slim taper file is hung on two arms operated 
by an eccentric or cam that gives a motion very similar to that of 
the human hand. All the teeth are filed from one side of the saw. 
The plunger and file are adjustable to various 
sizes of teeth and saws. 

55. Circular Rip-Saws. — In circular rip- 
saws, the hook or pitch, and the size and -p- 3^ 
shape of the gullet, or bottom of the teeth, 
are important. An insufficient amount of hook causes the teeth 
to scrape and tear the wood; the saw requires more power; it cuts 
slower and gets dull more quickly. Too much hook weakens the 
teeth and causes them to dodge or break. The shape of the gullet 
should be round to allow room for the shavings and saw-dust 
and, at the same time, to strengthen the base of the tooth. A 
square corner will be liable to cause a crack in the saw at the corner. 
A well formed tooth is shown in Fig. 38. The distance a is broad 
for strength. The gullet b is round and will hold sufficient saw- 
dust to keep the saw from choking. In Fig. 39, the gullet b is 
too small. The dotted lines show where it should have been filed. 





Fig. 38 Fig. 39 

Fig. 40 shows how they are often filed. A tooth like this could 
not possibly cut and remove the saw dust properly. It would 
furthermore be very liable to crack as shown in the illustration. 
Fig. 41 shows the lay-out for the teeth. Notice that the front 
of the tooth, if continued, would make a tangent with circle A, 
the diameter of which is one-half that of the saw. There is a 
difference of opinion as to whether the back of the tooth should 



54 



SCHOOL SHOP MAINTENANCE 



be filed any or not. The argument for not doing so would seem 
to be the best. If the tooth is filed on the front only, different 
filings will cause the tooth to appear in the positions shown by dotted 
lines in Fig. 41, and if the fine of the front of the tooth is kept tan- 





Fig. 41 



Fig. 40 

gent to circle A at 
each filing, the shape 
will be kept constant. 
If, however, the back 
of the tooth is filed 
near the point, it will 
be more difficult to 
keep this same shape. 

The first step, in fitting a circular saw, is to see if it is round. 
It can be made so by lowering the saw or raising the table until 
the saw rises just above the latter. By holding a piece of an old 
emery wheel on the table and pushing it gently against the saw 
while in motion, the points of the high teeth are ground down in 
line with the others. No more of the points should be ground off 
than necessary to bring all the teeth in fine. Remove the saw 
from the arbor and fasten it in a saw clamp. Very good clamps 
can be purchased which tilt at different angles to suit the operator's 
convenience. A good one can be made of a 13/2'' plank of the proper 
length to reach from the floor to the level at which the filer desires 
to work. There should be a slot near the top of the plank fitted 
w^ith a bolt on which the saw should be hung and drawn tightly 
against the plank by a large washer or another piece of plank. 
The slot permits of raising and lowering the bolt to accommodate 
different saws. 



FITTING SAWS 55 

In order to keep the teeth uniform, a template can be made 
from a piece of brass as shown in Fig. 42. A file, with a round 
edge, should be used for filing, as one with square edges would 
make corners in the gullets. The teeth should be filed square 
across the front edge and square across the back except for the 
upper half near the point w^hich should be slightly beveled, the 
highest portion being on that side towards which the tooth is 
bent. Often, the mistake is made of beveling the front as well 
as the back. This causes vibrations and "runs." If an emery wheel 
of the proper shape is available, the gullets can be rounded on 
that. A round file can also be used for this purpose. 

Having been filed, the teeth should now be set. In this con- 
nection it might be noted that it is perhaps justifiable to insist 
that teeth be set before being filed, for the process of setting is 
liable to injure the edge of a keen tooth. Every alternate tooth 
should be bent to one side and the remaining teeth to the opposite 
side. This can be done in several ways. A mechanic, if not 
particular, files a small chamfer on the edge of his' saw table, and 
laying the saw on the table, strikes each tooth a light blow, bending 
it over the chamfer. This is a make- 
shift method and does not insure an 
even setting. If the teeth are not 
evenly set the cut is not as smooth, 
and, as some teeth would have to do ^ , , 
more than their share of the work, ^ 
they become dull quicker than if they ^ \ 

were assisted by the proper working \ ^'~^^^^^^" ' 

of the faulty teeth. A setting stake Fig. 42 

can be purchased which has a beveled 

disc anvil over which the teeth are bent. The amount of set is 

adjustable. There are also spring saw-sets, larger than those for 

hand-saws, but working on the same principle. 

After setting, the teeth should b3 side-dressed with a fiat fib 
until the amount of set is the same on all teeth. This is determined 
by some gage. Fig. 43 shows a home made gage that is good. 




56 



SCHOOL SHOP MAINTENANCE 



The screws a, a, a project equally thru the wood. Screw b is 
adjusted so as to make c the distance from screw b to side of saw, 
equal to the set desired. A circular saw should have set no farther 
down the teeth than necessary to make it run free and the amount 
that the teeth bend to each side of the saw should be about 3^". 
56. Circular Crosscut-Saws. — Circular crosscut-saws are fitted 
in much the same manner as the rip-saws. The teeth, however, 




Fig. 43 



Fig. 44 



are different in form and have more bevel or fleam on the back and 
front. Fig. 44 shows crosscut teeth. The gullet should be round 
and the bevel should not reach to it, but about half-way down. 
A, Fig. 44 shows a tooth for soft wood and B one for hard wood. 
In using an emery wheel for gumming or rounding the gullets, care 
should be taken to prevent the saw from being heated to a blue 
color. It is better, in this process, to work around the saw a 
number of times, cutting a small amount each time, and thus 
prevent over-heating the teeth. 

If a crack forms near the rim of the saw, it can be kept from 
growing longer by drilling a small hole at the base of the crack. 

Tho it may cause temporary delay, much time is gained in 
the end by keeping the saws in good condition all the time. Touch- 
ing up the teeth often is a small job, but to wait until they become 
very dull makes a laborious job of the fitting. 



CHAPTER VII 
Brazing Band-Saws 

57. Brazing. — A good joining of band-saw blades by brazing 
is a knack not difficult to acquire, and one needs only to work 
carefully and accurately. Perhaps the best way to learn is to 
take short, broken pieces of a band-saw blade and practice on 
these, making a number of joints until always sure of a good 
braze. The beginner should start on a narrow blade, about ^" 
or so wide, and gradually try wider ones. As it is probably easier 
to make a two-tooth lap, i. e., lapping the ends a distance equal 
in length to two teeth, the novice should attempt this first, but 
a one-tooth lap is preferable on saws up to 5^" or ^" wide, as the 
strain in passing over the wheels of the saw frame is less liable to 
part it. 

The first operation in brazing is to examine the blade and see 
how much filing is needed. The lap or scarf will look like Fig. 45 
and should hz so made that the ''set" of the teeth where the ends 
join will match. If care is not 
taken in this particular, when 
the saw is set later on there 
will be two teeth next to each 
other which are set to the 
same side, and unless the 
operator has kept this in mind 
and started setting on the lap 
and finished at the lap, there 

will be trouble, for he will be setting a number of teeth to the 
opposite side from which they have been set before and this is 
liable to break them. A saw should have an even number of teeth 
in order to have them set alternately to the right and left thruout 
the length of the saw. After deciding where the joint is to be made, 

57 




Fig. 45 



58 SCHOOL SHOP MAINTENANCE 

it is best to first file the ends square with the sides; then each end 
can be placed on a strip of hard wood, Fig. 46, and held in place 
by a small clamp. The strip of wood is then fastened tightly in 
a vise and the end scarfed to appear like A, Fig. 45. One scarf 
will be on one side of the blade and the other on the opposite side. 
A flat hand or mill file should be used for this purpose. The laps 
should be perfectly flat surfaces and should fit each other nicely. 
They should be filed to almost a knife edge at the ends. Some 

prefer to draw-file the 
laps as a finishing 
touch. After being 
sure that the scarfs 
bear on each other 
evenly, carefully clean 
any grease or dirt from 
the filed surfaces. This 
can be done with muri- 
atic acid, slaked Hme 
or a compound made 
Fig. 4G purposely. It is very 

essential for a good 
braze to have clean surfaces. Now put the saw in the brazing 
clamp, Fig. 47, being sure that the edge, opposite the teeth, makes 
a good contact with the straight edge on the clamp and that the 
laps and teeth match up. A sHght allowance can be made for 
expansion of the saw upon being heated. When the blade is in 
proper position with laps over the center of the opening in the 
clamp, fasten it there with the clamp screws, not too tightly, how- 
ever, for the saw expands on heating and if not allowed to move 
under screws a trifle, it is liable to buckle near the joint. It could 
be straightened, but it is not necessary to have it buckle if the 
tension on it is proper. 

There are at least three ways in which the blades can be heated 
and a good braze made for practice. The author has his students 
use ah three methods, as the most desirable appliances are not 




BRAZING BAND-SAWS 



59 



always at hand. For the narrower saws, tongs will do, but for 
wider saws a heavier clamp and one including heating irons is 
necessary. The principle, however, is the same. The treatment 
for the narrower blades and tongs is as follows: After the saw is 
in place in the clamp, a flux is appHed to the scarfs. Lump borax 
works very nicely and is prepared by pulverizing, only as needed, 
and then mixing to a paste with water. Also there are compounds 
prepared expressly for this purpose. A piece of silver solder, tha 




Fig. 47 



size of the laps, is cut and cleaned, as was the scarf, and placed 
between the laps. Two pairs of tongs should be heated, one to a 
bright red heat — almost a yellow, but not a white heat, and the 
other to a dull red heat. Take the hottest tongs from the fire and 
scrape the inside surfaces clean with an old file, edg3 of a square 
iron or something similar, and than apply the tongs quickly to 
the joint, clamping it tight. The tongs should be a bright red 
color when applied or the solder will not melt and run out properly. 
When the solder can be seen to melt and run, the tongs should 
be carefully removed and dull red ones very quickly applied in 
their place. This change must be made quickly or the joint will 
open. The second pair of tongs should be left on until they are 



60 SCHOOL SHOP MAINTENANCE 

black. If only one pair of tongs is available, it can be heated to a 
bright red, and left on the joint until black. Sometimes the handles 
get pretty hot by that time and the temper of the saw is then 
hable to be injured, so a second pair is more advisable. 

When the saw is cold enough to handle, file the solder out of 
the joints, clamp the saw on the block of wood used for making 
scarfs and dress each side of the joint with a file until it is the 
same thickness as the remainder of saw. 

A second method is that of heating the joint with a blow torch 
to a bright red heat or until the solder melts and runs, and then 
clamping it tight with a pair of tongs heated to a dull red. This 
method is often used where no forge is handy. The tongs can be 
heated a trifle hotter than necessary with the blow torch before 
heating the joint and when the joint is hot they will have cooled 
sufficiently to be of the right temperature. 

In the third case, a bunsen burner is used to heat the blade. 
This is, of course, a slower process, but will answer the purpose 
if other equipment is not available. The tongs should be heated 
first, as when the blow torch is used. It may be necessary to 
use two burners in order to get the tongs hot enough. Be sure to 
allow for the cooling of the tongs while the joint is being heated. 

When brazing with the bunsen burner or blow torch, it may 
be found advantageous to wrap fine wire tightly around the laps 
after the solder is in place. Twist the ends of the wire at the side 
where they will not prevent the tongs from pinching the joint 
tightly. 

Where it is necessary to braze saws wider than 1", it is advisable 
to use a larger clamp fitted with two irons which can be heated 
and clamped in position on each side of the joint. These should 
be left there until cold. It is difficult to get even pressure over 
such a large joint with tongs. 



CHAPTER VIII 

Belting 

58. Belt Comparisons. — There are three kinds of belts in 
common use; namely, leather, rubber and canvas or gandy belts. 
Each has it advantages and disadvantages, and in choosing a 
belt, one should have in mind where it is to be used and how. 

Leather belts are the strongest, wear the longest, stretch the 
least, can be cut into narrower belts and are not injured by animal 
oils. However, the first cost is the greatest, and they are injured 
by water, steam, mineral oils and extreme cold or heat. They 
are not always uniform in thickness, and for that reason, stress 
may not be exactly uniform thruout a leather belt. 

Rubber belts are uniform in thickness, width and strength and 
make good pulley contact. Extreme temperatures will not harm 
them. They are not as expensive as leather, as far as first cost is 
considered, and are waterproof. But they cannot be cut into smaller 
belts to advantage, will not wear hke leather and stretch easier. 

Canvas belts have the lowest first cost, are strong, flexible and 
make good contact. They are uniform in width and thickness and 
consequently strength. They are not injured by oils, greases, 
steam or water and can be run with either side to the pulley. 
They cannot, however, be cut up into smaller belts, and, if broken 
or cut, easily fray. They stretch easily and shrink or expand 
with changes of the weather. 

If conditions are right for leather belting, and the belt to be 
chosen will be subject to hard and continuous wear, the purchase 
of a good leather belt will undoubtedly pay in the long run. 

59. Choosing a Belt. — The best grades of leather belting are 
taken from that part of the hide which runs parallel to and near 
the back-bone, and from the tail to a point just back of the 
shoulders. It is hard to judge a belt by merely looking at it, but 

61 



62 SCHOOL SHOP MAINTENANCE 

in general it is wise to choose the one made of the shortest laps or 
pieces. If long pieces can be seen in the make-up of the belt, it 
can be assumed that part of the neck of the hide was used, or else 
parts farther removed from the back-bone. These parts are easily 
stretched. Some manufacturers will combine the poorer grades 
with the best grade, putting the latter on the outside. This makes, 
perhaps, even a poorer belt than if it were made entirely of the 
inferior grade of leather, for the parts do not stretch alike, and 
consequently there is an uneven stress thruout the length of the 
belt. The leather that is strong, close of texture and less easily 
stretched is that part close to the spine, and such strips will be not 
over 4 ft. long. Narrow, thick belts are generally more satis- 
factory than wide, thin ones, especially at high speeds. The latter, 
if run fast, run in rolls or waves with considerable flapping on the 
slack side. This tends to wear the belt rapidly. A light, double 
belt is considered better than the same thickness in a single belt. 
It is not good pohcy to use double belting for twisted belts running 
fast, nor in places where water or oil come in contact with it. It 
is advisable to use double belting on pulleys larger than twelve 
inches in diameter. 

60. Care of Belts. — Leather. The hfe and service of a belt 
depends upon the care it receives. Rosin is often used to prevent 
the slipping of belts, but it is injurious to the leather. Neatsfoot 
oil (if not a substitute for the real thing) is good. Boiled linseed 
oil gives good clinging qualities. Castor oil does very well. If a 
belt becomes glazed and dry, rub with a cloth dipped in kerosene 
and apply a thin coat of the following mixture to the driving side: 
Two parts beef tallow, one part cod liver oil (by weight). Melt 
the tallow, and when cool enough to insert the finger, stir into it 
the cod liver oil. Continue stirring until cold. Do not allow 
lubricating oils to come in contact with leather belts, if it can be 
avoided. If belts do become soaked with oil, pack in sawdust, 
wash in naphtha soap and apply the above dressing. 

Rubber. Keep oils and greases off. An occasional application 
of the following will add to their Hfe: Equal parts of red lead. 



BELTING 



63 



black lead, French yellow, and litharge, mixed with boiled linseed 
oil and enough japan drier to make it dry quickly. Paint it on 
and give it time to dry thoroly. 

Stretching. A new belt should be stretched before using. This 
can be done by fastening the ends to the floor with blocks, and 
raising the center on blocks and leaving it thus for some time. 




Fig. 48 

This should be done before measuring for length or joining ends. 
If not stretched, then a belt should be from one to two inches 
shorter than the actual measurements around the pulley, to allow 
for the stretching which will result when first put to use. Never 
''run on" a wide belt if it can be avoided. Use a stretcher in 
joining ends. Fig. 48, and lace or splice them on the pulleys. In 
the stretcher shown in Fig. 48 two bolts, with nuts or winged 
nuts, fasten the pieces in each clamp tight against the belt. With 
a wide belt and a hard pull, it is sometimes necessary to drive two 
nails thru each clamp and the end of belt to keep it from shpping. 
This stretcher can be easily made of good hard wood and threaded 



64 



SCHOOL SHOP MAINTENANCE 



rods or bolts of the proper size. For belts of medium size use 
about y^' bolts and XYl' maple strips for clamps. Put washers 
under heads and nuts of all bolts. 

6 1 . Applying Belts to Pulleys. — There is a difference of opinion 
as to which side of a leather belt should be next to the pulleys. 
The totally uniformed person would put the rough or flesh side 
next to the pulleys, and the hard, smooth or grain side out. It 
is the more natural way because the hard, smooth side is the better 




Fig. 49 

looking. Whichever side is used, that same side should be in 
contact with all the pulleys over which the belt runs. If the flesh 
side is next to the pulleys it should have a coat of currier's dubbing 
and several coats of boiled linseed oil every year. The grain or 
hair side should have castor oil or neatsfoot oil from time to time 
to keep it pliable. 

The claim is made that a belt is weakened when the grain side 
is next to the pulleys because the natural growth of the hide is 
being worked against. Others argue that the flesh side stretches 
easier and should be on the outside where the greatest length of 
belt is. The more common and probably the best practice is the 
former method, i. e., to have the grain or smooth side against the 
pulleys. It is certain that there is a better contact between belt 
and pulleys this way and more horse-power is obtained. 



BELTING 65 

Rubber belting should be applied with the seam side away from 
the pulley. Where a belt is spHced with glue, there is also a differ- 
ence of opinion as to application. It is generally assumed, however, 
that the end of the outside lap should point in the opposite 
direction from the belt motion, to prevent the air resistance from 
opening the splices. This rule applies to both leather and rubber 
belting. 




Fig. 50 

Where belts run in a position more nearly horizontal than 
vertical, there is a sag between the pulleys. The sag in the lower 
half of the belt tends to decrease the amount of belt that actually 
would touch the pulleys were the belt in a straight line between 
them. The amount of pulley in contact with the belt is called the 
arc of contact. The sagging at the tops tends to increase the arc 
of contact and, as the horse-power is increased by adding to the 
contact distance between pulleys and belt, the direction of the 
belt should be such that the sagging at the bottom will be decreased 
or that at the top increased, or both. Thus a rule for this could 
be stated as follows: The direction of the belt should be from the 
top of the driving pulley. See Fig. 49 for the right and wrong 
methods of drive. 



66 



SCHOOL SHOP MAINTENANCE 



62. Joining Belts. — In lacing belts observe the following 
rules: For belts from l" to 3" wide make lioles from Yi' to Yi from 
sides, and for thoze from 3" to 10" w^ide make holes from J^" to 
^/^' from sides (not ends). Always have 



\ 



PULLEY SIDL^ 
Fig. 51 



the ends of the belt square with the sides, 
Fig. 50. Use an oval punch, making the 
long way of the hole parallel to the long 
way of the belt. Do not make holes in 
rubber or canvas belt with a punch but 
use an awl or sharpened nail. Make holes 

only as large as necessary to get the lacing thru. The punch cuts 

the strands of the material but the 

awl wedges an opening between 

them. The lacings on the grain or 

pulley side of the belt should run 

parallel to the length of the belt. The 

grain side, the side commonly applied 

to the pulley, is the smooth, hard 

looking surface. It is the outside or 

hair side of the hide. Make crossings 

of lace come on the outside of the 

belt. After lacing with rawhide or 

wire, flatten the lacings with a wooden 

or rubber faced mallet. Do not pull 

the lacings tight on one end of the 

joint until the other end has been 

brought together with laces. Use 

pliers in pulling lacing. Fasten the 

ends of laces by pulling them thru a 

small hole and cutting a slit on each 

edge of the lacing close to the belt. 

See A^ Fig. 51. These sHts or ears 

will spread out on either side of belt close to the hole and prevent 

the end of the lacing from coming thru. 

63. Lacing 2" to 4" Belt with Rawhide. — Use method shown in 




"vv 



\y^v— 



Fig. 52 



BELTING 



07 



i^igs. 52 or 53. If the method illustrated in Fig. 52 is used and 
the number of holes in each end is odd, start the lace by putting 
it up thru 3 and 8 referring to the holes numbered on A, Fig. 52, 
from the grain on the inside of the belt. The end that came thru 





Fig. 53 



Fig. 54 



2 IN. 
BELT 
<P 



2|FT. 
LACE 



3 is then crossed over and inserted back thru hole 8 and up thru 
3 again, then down thru 9, up thru 2, down 10, up thru 1, down 
thru 10, up 1, down 9, up 2, and finally down 8. It is then fas- 
tened thru hole 12 by sKtting. The other end, which came up 
thru 8, goes down 4, up 7, etc. 
and finally goes down 3 and is 
fastened in hole 1 1 similar to the 
other end. If method in Fig. 53 
is used, start by putting the lace 
thru hole 1 from the outside and 
proceed as shown by arrows in the 
sketch. For simpHcity the lace is 
shown by one line only. Finish 
by putting the ends thru holes F and shtting as shown in A . Fig. 51. 
For light work on large pulleys use single butt lacing method 
shown in A and By Fig. 52. 




Fig. 55 



68 



SCHOOL SHOP MAINTENANCE 



64. Other Rawhide Laces. — Figs. 56, 57, and 58 show three 
other common methods of lacing belts with leather. In each 
illustration S indicates the point where the lace is started, and 
F the point where it is fastened. The illustrations suggest the 



DOUBLE 
STRAIGHT 



y < (> 

a a < 

< 




Fig. 56 

steps in the process of lacing. One half of the lace is completed 
first; then the lacing is brought across to the other half and 
finally back to the center, where it is fastened as suggested in 
Section 63. Care must be taken to start the work in such a way 
that the strands fall parallel to the direction of the belt on the 
pulley side and that all angular strands come on the opposite 
side. 



^^ 



STRAIGHT 
LACE 



Fig. 57 




65. Heavy Work on Large Pulleys. — Use butt lacing methods 
in Figs. 54 and 58. In Fig. 54 start the lace in hole L The arrows 
and numbers show the steps to take with the lace. Put the ends 
thru hole 22 and sHt. In Fig. 55, start by putting the lace up thru 



BELTING 



69 



holes 1 and 2 from pulley side. Put the end, that came thru 2, 
down 3 and across underneath belt and up thru 4. Repeat this 
operation clear across that half of the belt. Do the same on the 
opposite half with the other end. When the edge of the belt has 
been reached, work back the same way but putting the lace also 
thru holes in rows A-B and C-D as you do so. This will give a 
double lacing across ends of belt and a single lacing thru holes 
in rows A-B and C-D. Fasten the ends in usual method in T and T. 



-XV^ 



Mil 



qb 



co 



MM 



PULLEY Slot 



Fig. 58 



yv\ 




Rubber and canvas belts, doing heavy duty on large pulleys, 
should be laced with method shown in Fig. 58. For lacing by this 
method see previous paragraph. For small pulleys use double 
hinge method in Fig. 59. In this method, the lace should be 
started by putting it down thru hole 1 from the top and by bring- 
ing it up between the ends of the belt at point A. Put it down 
thru 2, up between ends again and down 3. Now up between ends, 
down 4, up between ends and down 5. Continue across the belt 
similarly. Tie one end by putting it down thru hole B and up 
thru 1 and sHtting it close to 1. Tie the other end likewise at 
hole C Dotted lines, in drawing, show lacing on under or pulley 
side of the belt. Full Hnes show it on the top. 



70 



SCHOOL SHOP MAINTENANCE 



66. Lacing with Wire. — In using wire, follow directions on 
the box it comes in. There are five sizes of wire and the size of 
wire to use will depend upon the width and thickness of the belt. 

Belts should not be laced with wire if 
they are to be shifted by hand as the 
ends of wire will almost surely tear 
the flesh of the operator. Where a 
belt, more than four inches wide, is to 
be laced with wire, it is a good plan 
to have the wire in two shorter lengths 
rather than one long one. The advan- 
tage is, that in case the wire breaks in 
one place, the belt will still be held 
in place by the good wire and the 
time required to repair the belt will 
be less. In leather belts, some prefer 
to cut a small groove from awl hole 
to edge of joint on the pulley side for the wire to lie in. This will 
lessen the wear somewhat. In any case the wire should be pounded 




Fig. 59 




■\/v^ 



3 4/5 6 7 6 

^ o o o o 



r€) O O O O 



Fig. 60 



flat with a mallet. This groove can be made with a knife or a 
veining tool but should be shaUow. The holes for the wire can 



BELTING 



71 



be made with an awl or finishing nail ground sharp, but should be 
no larger than absolutely necessary. They should be about Y% 
from the ends of the belt and Ys apart for a 4" to 6'' belt. In lay- 



HOOK 




5ECTI0n ON A-B 



(:^:^v;:^^^'G P)(a^^);^v^:.•■^^;r^ 

Fig. 61 



ing out holes, be careful to get them exactly opposite each other 
on each end of the belt. Always have the ends of the belt square 
with the sides. Use a square. Do not guess. See Fig. 50. Noth- 
ing will get a belt out of shape more quickly than having joined 
ends out of square. 

Use the method shown in Fig. 60. Start in hole 4 and take 
steps in order of numbers and in direction of arrows. 

67. Patent Fasteners. — The patent fasteners shown in Fig. 
61 are in common use now and are put into a belt with a small 
machine. One style of machine is 
called ''The CHpper." This is a 
very good way of fastening a belt 
for small or large pulleys. It makes 
a hinge joint and the holes are not 
in Hne, thereby not causing the belt to break off as quickly as in 
some styles where the holes are in line. A stiff rawhide pin is in- 
serted thru the loops of wire. 

Another kihd of patent fastener is that in which a coil of wire 
is run thru the ends of the belt with a machine leaving loops thru 




Fig. 62 



SCHOOL SHOP MAINTENANCE 



which a rawhide pin is inserted; this fastener is similar to the style 
shown in Fig. 61 except that the holes are in hne and, because of 
this, the belt often breaks off in a line thru the holes whereas, if 
they are zigzagged, this seldom happens. 




BLAKE\S HOOKS 
Fig. 63 



Belt hooks of the style shown in A, Fig. 62 are only good for 
quick repair jobs. They are put thru punch holes from the out- 
side of the belt so that the points run against the pulley. They 
are hammered fiat with a mallet. They should b3 no farther apart 




Fig. 64 



than an inch. The style of hook, shown in B, Fig. 62, is also for 
hurry up jobs and can not be highly recommended. 

The Alligator Steel Facing, similar in principle to the style in 



BELTING 73 

Fig. 61 is one of the best. In place of wire hooks a perforated 
steel plate with loops is clinched to the ends of the belt and a 
rawhide pin is inserted. 

Blake's Belt Hooks, A, Fig. G3, are becoming quite generally- 
used. The ends of the belt are squared and clamped together 
against a block of wood in a vise, Fig. 64. A slit is made with a 
carpenter's chisel of the proper width and ground to a long bevel, 
or, better yet, with a piece of 3^" or ^" band-saw like Ay Fig. 64. 
This should be ground sharp and tempered. Both ends of belt 




LENGTH or 5PUCL 

Fig. 65 

are cut at once as shown in Fig. 64. The hooks are then inserted 
as shown in B, Fig. 63. The belt, when completed, will look like 
C, Fig. 63. 

68. Cemented Splices. — A cemented splice is the most 
satisfactory way of joining leather belts. The ends should be 
squared carefully and tacked to a board with two small nails, 
Fig. 65. On the board, at the proper distance back from the end, 
place a mark showing where the splice is to end. With a sharp 
plane, pare each end of belt, being careful to have laps on opposite 
sides of the belt. On belts from 1" to 9" wide laps from o" to 10" 
long. On wid^r belts make laps as long as the belt is wide. 

After scarfing the ends, place the belt on a straight Hne drawn 



74 SCHOOL SHOP MAINTENANCE 

lengthwise of a board, as in Fig. 63, or against a thin strip of wood 
tacked on the board as a straight edge, or have the belt line up 
with the edge of the board at the edge. Fit laps carefully and apply 
some good belt cement between the laps. Knead the joint well 
with a piece of a broom stick used like a rolling pin. Over the 
joint, lay a piece of board and clamp the two boards together 
tight. Leave them thus for 24 hours to allow the glue to thoroly 
set. A good glue can be made by heating a half ounce of white 
lead with a half pound of good white glue in a double boiler or 




JOINT 
MARK 



Fig. 66 

glue-pot. Stir this mixture constantly until a thick paste is ob- 
tained. When it is to be used it should be made into a thin paste 
with grain alcohol and, if possible, warmed w^hen apphed. 

Rubber belts are spliced by making laps as in leather belts only 
that rubber cement is used. Apply several coats, allowing each 
to dry for several minutes before putting on the next coat. The 
joints should be clamped tight, and when dry should be further 
re-inforced by a few copper rivets. The laps should be the same 
thickness as the rest of the belt whether in leather or rubber belts. 
Pound and roll the splice to get all air pockets out. Warming the 
belt and boards will improve conditions, particularly if it is neces- 
sary to make the splice in a cold place. 



BELTING 75 

69. Don'ts. — Do not forget to square ends of belt. 

Do not punch larger holes or use larger laces than necessary. 

Do not use rosin. 

Do not become too lazy to gather interest from your investment 
in a belt by keeping it pliable and free from dirt and mineral oils. 

Do not use a style of lacing like that in A, Fig. 60 if a binder 
pulley is to be used. This is a fine way of lacing a belt because 
none of the belt is cut away by belt holes but the method of join- 
ing leaves a ridge on the outside of the belt which does not allow 
the belt to work well with a binder pulley. In this case, the hinge 
lace method in Fig. 59 or the Alligator Steel Lacing would be more 
suitable. 

70. To Find the Horse-Power Which a Belt Will Transmit.— 
Multiply the width of belt by diameter of driven pulley in inches and 
multiply this product by R. P. M. of driven pulley. Then divide this 
final product by constant 2,750, and the quotient will be the horse- 
power. 

Example: What horse-power will a 12" belt transmit on a 36" 
pulley running 200 R. P. M.? 

Answer: 12 x 36 =432, and 432 x 200 = 86,400, 86,400 divided 
by 2,750=31.4 H. P. transmitted. 

71. To Find Width of Belt Required for a Given Horse-Power. 
— Midtiply the horse-power by the constant 2,750, then multiply the 
diameter of driven pulley by the number of its revolutions, and divide 
the first product by the latter, and the quotient will be the width of 
belt required. 

Example: What width of belt will be necessary to transmit 20 
horse- power over a 30" pulley running 200 R. P. M.? 

Answer: 20 x 2,750=55,000 and 30 x 200=6,000, 55,000 
divide by 6,000 =9]/^" width of belt required. 

72. With Horse-Power and Width of Belt Given, Find the 
Diameter of Driven Pulley Required. — Midtiply the horse-power by 
constant 2,750, then midtiply revolutions of pulley by width of belt 
and divide the 'first product by the latter. The quotient will be the 
diameter needed. 



76 SCHOOL SHOP MAINTENANCE 

Example: What should be the diameter of driven pulley at 200 
R. P. M. to transmit 10 horse-power with a 5" belt? 

Answer: 10 x 2,750=27,500 and 200 x 5=1,000. 27,500 
divided by 1,000 =27y2 dia. of pulley. 

73. To Find the Length of Belt Wanted. — Add the diameters of 
both pulleys together, divide by 2 and multiply the quotient by 3.14. 
Add this product to twice the distance between the centers of shafts in 
inches and the sum will be the length of belt required. 

Example: The diameter of a large pulley is 36" and the diameter 
of a small pulley is 14". Their centers are 12 ft. apart. What length 
of belt is needed? 

Answer: 36 plus 14 =50, 50 divided by 2 =25, 25 x 3.14= 78.50, 
2 X 12 ft. =288 inches. 288 inches plus 78.50 inches =366.5 inches 
or 30 ft. 61 2 inches. 

74. To Find the Horse-Power of a Driving Pulley. — Multi- 
ply the circumference of the pulley by revolutions and multiply this 
product by width of belt. Divide the final product by 600. Circum- 
ference = dia. in inches x 3.1416. 

Example: What is the horse- power of an 18" pulley making 
160 R. P. M. with a 6" belt. 

Answer: Circumference =18 x 3.1416 =56.55 and 56.5 Xl60 = 
9,048, 9,048 x 6=54,288 and 54,288 divided by 600=9.04, the 
horse-power wanted. 



CHAPTER IX 

Babbitting 

75. Babbitt Metal. — The term ''babbitt" comes from the 
name of the inventor, Isaac Babbitt, who developed the recessed 
box with the soft metal lining for machinery bearings. Babbitting 
means the pouring of babbitt metal into a box, thereby making a 
bearing for the shaft that runs in the box. 

The formula for the original babbitt has been lost, but it 
probably consisted of 90 parts tin, 3.7 parts copper and 6.3 parts 
of antimony. The high cost of tin, however, makes it expensive 
and many alloys of varying compositions have been put on the 
market as a substitute, and many of them named ''babbitt". 
Other compositions having in them lead or zinc have become 
common. White metal alloys have several advantages over others. 
They are easily melted in an iron ladle over bunsen burners or 
blow torches, or in a forge. Bearings from them may be made with 
practically no special tools and the time required to run a bearing 
is not long. They have good anti-frictional qualities and wear 
well. When badly worn, they are easily chipped out and replaced. 

The composition of the metal should depend upon the purpose 
for which it is to be used. For high pressure bearings at high or 
fast speed, an alloy called Babbitt Metal Best, and having the 
composition stated in the paragraph above, is very good. For 
medium pressure and medium speed, a metal containing 14.35 
parts tin, 17.73 parts of antimony and 67.89 parts of lead will 
be very serviceable and is cheaper than the former. An alloy, 
having this proportion, is on the market and is called Graphite 
Bearing Metal. It has no graphite in it, however. 

For shaftings, which ordinarily run at comparatively slow 
speeds. Anti-friction Metal is good and has a composition of 88.32 
parts lead and 11.68 parts antimony. 

77 



78 SCHOOL SHOP MAINTENANCE 

The above proportions are the findings of an analysis of bearing 
metals (about 50 in number) made by The Pennsylvania Railroad 
Co. at their laboratory at Altoona, Pa. 

76. Preparing to Pour Babbitt Metal. — If the job be that of 
replacing a worn bearing, the first operation, after the shaft is 
out, is to remove the old babbitt. This can be done with a cold 
chisel by chipping. It is very important that all water and oil 
be removed from the recesses. If the water is not removed, it 
will suddenly turn into steam when the hot metal is poured upon 
the box, and, increasing in volume over a thousand fold, will 
''blow" and in all probabihty cover the operator with molten 
metal, doing injury to the flesh and eyes. A little oil will not 
blow but it will blister the surface of the metal and it should, 
therefore, be removed. Dirt, left in the recess, will also cause 
trouble for, if loose, it will be floated by the heavy metal and will 
make a pit in the bearing surface. 

Oil and water can be removed with a blow-torch, if one is at 
hand. Another way to remove it is to pour gasohne into the box 
and burn it. Care should be taken to keep gasoHne away from 
any flame. Sometimes it may be convenient to put the box in a 
forge to dry it. In field work, when nothing else is handy, a fire of 
wood under or on top of the box will dry it out. 

77. Alignment of the Shaft.^When it is time to ahgn the shaft 
or locate it properly in the box, it is better to use a mandrel of the 
same size or a trifle larger, for, whether the shaft or a mandrel 
is used, conditions are made more ideal by heating the box or the 
shaft or the mandrel and, if the shaft is heated or hot metal is 
poured on it, it is liable to be warped, sprung and thrown out of 
ahgnment. This will cause the bearing to wear out quickly or 
burn out. If heated with a blow-torch, heat will not be evenly 
distributed all around the shaft in all probabihty, and if the hot 
metal is poured down thru an oil hole, it will strike in one place on 
the shaft and cause it to expand there more than elsewhere. The 
metal, cooling quickly about the shaft and shrinking tight against 
it, will hold it tightly in this form (expanded on one side) until 



BABBITTING 79 

cool. Careful testing will show that the shaft is coiivexed laterally 
at the point where the molten metal struck it. The amount may 
be small but the uneveness may be felt if the shaft is turned by 
hand, and, if turned by power at fast speeds unsatisfactory results 
will, in most cases, follow. For the above reasons, if several 
bearings are to be made, it is better to use a mandrel. A mandrel 
can be easily made on the lathe and kept for this purpose. In 
an emergency, a piece of pipe of the right size and wrapped with 
paper may be used. 

The matter of aligning cannot be treated of, except in a general 
way, for seldom are conditions twice alike. However, there ara a 
few considerations which should have careful attention when 
making a new bearing: For instance, consider a shaft on which a 
circular saw runs. It is important that the shaft or arbor be 
parallel to the saw table when the latter is at O degrees or in a 
horizontal position. If the saw table is level then the arbor also 
should be level, and a spirit level can be used in setting the mandrel 
in place for babbitting. It is also important that the saw rotate 
in a plane parallel to the fence or stock guide on top of the table. 
Again, if the bearing being made is for a grindstone shaft, and 
the frame of the grindstone is fastened to the floor and cannot be 
easily moved, it is necessary to have the shaft at right angles 
to the belt which drives it; otherwise the belt will not stay on the 
pulley. In this case the easiest way to aHgn the shaft is to make 
the distance from each end of the shaft to the line shaft the same. 
If one were pouring the middle bearing of an overhead line shaft 
having three bearings, he would wish the shaft to be straight; 
if not supported in the center, the weight of the shaft would cause 
it to sag there. In this case the best way to ahgn the shaft would 
be with straight edge and level as explained in the section on 
shafting (Page 18). The shaft can be kept from sagging in the 
center by blocking it or tying it up. In a similar way, the hori- 
zontal alignment can be made, i. e., by stretching a wire horizcn- 
tally opposite t*he center of the shaft at precisely the same distarxe 
from the shaft at each end, and tying the centre of the shaft so 



80 SCHOOL SHOP MAINTENANCE 

that it measures the same distance to the wire as do the ends of 
the shaft. 

The matter of ahgning, then, is one to be considered differently 
for nearly every condition under which a bearing is poured and 
calls for good judgment and mechanical sense. Ahgning a shaft 
for a grindstone is a comparatively simple job but getting a crank 
shaft for a gas engine ahgned properly calls for considerable skill. 
The matter of holding a shaft or mandrel in its place, after it has 
been ahgned, is a varying problem also, but, in most cases, wood 
blocking will suffice for this purpose. In any case, shafting should 
be substantially fixed so that it will not move after much time has 
been spent in ahgning it properly. 

78. Preparing the Shaft. — The next step is to prepare the 
shaft or mandrel so that it will leave a smooth surface on the 
bearing metal. Some mechanics chalk the mandrel. This will 
do, provided the mandrel is smooth and the box is of such a type 
as to allow the mandrel to be heated before the metal is poured. 
If the metal is poured around the shaft itself and there is objection 
to heating the shaft, as there well might be, then a piece of good 
quality writing paper wrapped about the shaft will protect the 
latter and leave a smooth surface on the bearing metal, and, in 
case the mandrel could not be heated, this paper acts as an insulator 
and prevents the metal from cooling too quickly, leaving bhsters 
and folds on the bearing surface. It also prevents the contracting 
metal from gripping the shaft quite so tightly and makes subse- 
quent removal of shaft and scraping of the bearing less difficult. 
The paper should be lapped only about J^" and glued with thin 
glue or shellac. 

After gluing the paper, plans for an oil groove can easily be 
made by rubbing clay on a small cord or wrapping string and 
putting the latter around the shaft. One turn around the shaft 
directly under the oil hole in the box should first be made and a 
knot tied. Then each end of the string should be wound spirally 
around the shaft towards an end and in such a direction that the 
turning of the shaft will cause the oil to work out along the groove 



BABBITTING 



81 



that is to be left by the cord. That is, wind each end in the direc- 
tion the shaft turns, Fig. 67. Make only one to three turns about 
the shaft with each end and go no nearer the end of the bearing 
than about %" and fasten the string there by wrapping it square 
around the shaft once and tying it. This method can perhaps be 
more easily used on a spHt box than a sohd one but, on the latter, 
it can be used by gluing the paper around the shaft just at one side 
of the box, tying the string around it there and finally shpping the 




Fig. 67 



paper and string gently into place in the box, taking care that the 
center knot on the string lines up with the oil hole in the box. 

79. Damming up the Box. — The next step is that of damming 
up the box so that the hot metal will not run out. A good material 
for this purpose is clay. It should be no wetter than necessary 
to mold properly, else steam will be formed and a "blow" result. 
A "blow" means the scattering of the hot metal by the formation 
of steam. If a number of bearings are to be poured and the 
material is to be used for damming again and again, putty mixed 
with asbestos ^\\\ not dry out like clay, and requires mixing but 
once each time bearings are to be poured. Putty, if not mixed with 



82 SCHOOL SHOP MAINTENANCE 

the asbestos, will get very soft when warmed and will not hold 
the molten metal in the box. 

80. Melting the Metal. — While this process of damming is 
going on, the babbitt metal can be melting. The melting place 
should be as close to the pouring place as possible so as to avoid 
the cooling of the metal between the fire and the box. If it is 
necessary to carry the metal some distance, it will require heating 
to a little higher temperature in order to allow for the cooling that 
will take place when it is carried to the place of pouring. Enough 
should be melted to allow plenty for filling the box and some for 
a possible leakage. Much time will be wasted if it becomes neces- 
sary to chip the bearing out again and pour over because there 
was not enough metal to fill the box. 

It is a common fault to overheat babbitt. This makes it 
brittle and may cause a loss of some of the properties thru volatiK- 
zation. It should not become so hot as to show a reddish purple 
tinge on top of the molten metal. It should have a yellowish color. 
A practical test that can be relied upon is that of inserting a 
piece of white pine into the metal. After immersion for about 
three seconds, it should be darkly browned, but not charred. 

81. Pouring the Metal. — In pouring, it is important that there 
be plenty of air vents, in order that no air bubbles form, and so as 
to allow the escape of steam. In case there is only one oil hole, and 
that one is being used to pour into, air vents can be made in the 
clay at each end of the box by packing the clay around a match 
or nail and building it up high so that molten metal will not run 
away and make it difficult to fill the box. Where possible, pieces 
of cardboard, carefully fitted around the shaft at the end of the 
box and held there by the clay, will add to the appearance of the 
ends of the bearing as well as prevent the clay from drying out 
so quickly and forming steam. 

There are two types of boxes in common use, namely open 
and closed boxes. By the former is meant a box in two halves 
spUt thru the center lengthwise. The two halves are held together 
by set-screws or bolts. Between the halves are shims. Shims are 



BABBITTING 83 

thin pieces of brass or other metal, or pieces of oiled paper or card- 
board. Their purpose is to make the bearing adjustable for wear. 
As the bearing becomes worn layers of the shimming material 
may be taken out, allowing the halves to fit closer together and 
thereby taking up any play that there may be between the bearing 
and the shaft. 

The closed box is one that is not spHt and is not adjustable for 
wear except by a new pouring. 

Open boxes can be poured in two ways, namely, pouring each 

half separately or pouring both at once. Fig. 67 shows the lower 

half being poured. Notice the blocking which holds the shafting 

in place. On each end of the box are pieces of cardboard, B, cut 

as shown in Fig. 68. Notice the slit that has been made from the 

edge of the cardboard to the hole for the shaft. By springing the 

cardboard, it can be easily forced around the shaft. Against the 

cardboard is packed clay to keep the metal from running out of the 

box. Around the shaft is placed a thickness of paper held in place 

by pasting the edges and assisted by a cord which has been rubbed 

with clay and is used to form an oil groove. Notice that it is 

wound spirally and in the direction of the turning of the shaft 

which in this case is clock-wise. The metal is poured into the lower 

half until it is full. Heating the box on the outside will assist in 

making a smooth surface by keeping the metal from cooHng too 

quickly. This can be done with a blow torch. When 

the metal has set and is cool enough to work, that 

part of the metal which rises above the top of the box 

is cut away with a cold chisel. The cutting should be 

done lengthwise of the shaft and care taken not to cut ^. 

Fig. 68 
or score the latter. In fact, if a little ridge of metal is 

left close to the shaft it will do no harm and can be scraped off later. 

Shims, of the proper size and shape to fit the flat surfaces of metal 

on each side of the box, are now cut and put in place and the upper 

half is fitted over the lower one. These shims should total about 

y^' in thickness*. The upper box is securely fastened and the ends 

are banked with clay. Fig. 69. One important point to remember 




84 



SCHOOL SHOP MAINTENANCE 



is that there should be an air vent or two for steam and air. If 
there are two oil holes in the upper half, one of them can be used 
for pouring and the other for an air vent. If there is only one hole 
then a vent should be made in the clay at the end of the box. 
In Fig. 69, nails can be seen at the end of the box about which 
clay was packed. When the nails were removed vents were left. 
In this picture, clay can also be seen built up around the oil hole 
to facihtate pouring. 




Fig. 69 



In case there is no oil hole in the upper half of the box, the metal 
will have to be poured in the end of the box as shown in Fig. 70. 
A port is also made here by building up with clay. If the box 
was vertical rather than horizontal, it would be necessary to pour 
it at the end; only, in this case, the upper end of the box would 
not be clayed and would thus serve for both a pouring port and a 
vent. Any oil holes would be filled with clay. 

In pouring both halves at once, shims are placed between the 
halves, as explained above, together with a piece of cardboard 
which is notched as shown in E, Fig. 71 and should rest against 
the shaft. The total thickness of the shims and the cardboard 



BABBITTING 



85 



should be a trifle more than J-g". The notches should be made 
twice the size and distance apart shown in the drawing for the 
metal must run thru them in order to fill the lower box, and if too 
small the box will not fill easily; whereas, if they are too large, 
trouble will be encountered in breaking them apart. This card- 
board is to make separation of the halves easy. The halves are 
broken apart by striking several snappy blows with the cold chisel 
at the parting of the halves after the shims have been removed. 




Fig. 70 



82. Scraping the Babbitt.— To get a good bearing between 
the metal and the shaft, the metal must be scraped. There are 
many good bearing scrapers on the market. A very good one can 
be made out of a half-round wood file by grinding it smooth and 
then forming it to the shape shown in, D, Fig. 71. . The edges 
should be ground and whetted sharp as shown in the cross section 
view, C, in ths same figure. 

The first operation, in fitting the bearing to the shaft, is to free 
the corners so they will appear like spaces, .1, Fig. 72. This 
should be don(5 on the lower half and will prevent a possible 
pinching of the shaft at the corners. The shaft should be free 



86 



SCHOOL SHOP MAINTENANCE 



for a distance of ^i" down from the parting on the lower half and 
an equal distance up on the upper half. After freeing the corners, 
a little Prussian blue, or lampblack mixed with oil, is rubbed on 



StCTlONONA-B 

cl 




the shaft and the latter is carefully lifted to its place in the bearing, 
given several turns and removed. The high places or the points 
in the bearing that touched the shaft will be colored and the other 
places will not be. By taking the scraper and removing a slight 




bit of metal from these high places a more complete touching of 
the shaft and the bearing will be effected. This process must be 
repeated a number of times until approximately 75 per cent of 
the bearing touches the shaft. Care should be taken not to get 



BABBITTING 87 

too much color on the shaft for it will mark the low places as well 
as the high. Enough color will generally remain, after the first 
application, to color the shaft two or three times before it is neces- 
sary to put more on. When more than one bearing is being fitted 
for the same shaft, they should be scraped in together, i. e., one 
bearing should not be completed without fitting the other, for 
if this is done the scraping of the second bearing will lower the 
shaft and throw it out of alignment with the first no matter how 
carefully it may have been fitted. 

When the lower half of each box has been completed, the upper 
halves are put in place with no shims and marked by turning the 
shaft. They are scraped to fit. 

The shims should now be inserted between the halves. The 
thickness of the shims should be the same on each side of the box. 
A good shim stock can be obtained which is made of very thin 
sheets of brass lightly soldered together. These thin sheets can 
be peeled off with a knife making possible a fine adjustment of 
the bearings. The amount of shims between the boxes should be 
such that the shaft will be free to rotate when the boxes are fastened 
tight, yet there should be no noticeable play at right angles to 
the shaft ; or, in other words, up-and-down play. In case of a heavy 
shaft, this can only be determined by prying the shaft up with a 
bar or stick. A fitting, that was just right when first fitted, will 
generally be found to be loose after a little running caused by 
the ''fitting in" of the shaft, and some of the shim stock will have 
to be removed to do away with this play of the shaft. It is better 
to remove shims after a little running than to fit the shaft so tight 
at first that no shims will necessarily need to be removed later on. 
If the shaft is fitted too tight there is danger of burning out the 
bearing, due to the extra friction. A new bearing should be kept 
especially well oiled at first. 



CHAPTER X 

Adjustments of Woodworking Machines 

83. The Circular Saw. — Knowledge of the care that should 
be given woodworking machinery and the proper adjustments will 
be gained more from experience than it will from explanations 
found in texts. 

The circular saw should be kept well oiled on the arbor bear- 
ings. The sliding table and tracks should be kept free from saw- 
dust and gummed oil. Clean them frequently with kerosene or 
gasoline, and rub a film of oil on the bearing surfaces with the 
fingers. There should be but a very shght bit of end play in the 
arbors. The bearings should be kept as tight as possible without 
pinching the shaft. The screw that tilts and raises or lowers 
the table should be well lubricated and kept free from dirt. 

84. The Jointer. — Requires a fine adjustment of knives and 
table in order to do good work. Assuming that the table and knives 
are entirely out of adjustment, the first step in an attempt to put 
the jointer in good working order would be to locate one knife 
in its place in the cutter head. The cutting edge of the knife 
should project from the head about %" to '%{' and this distance 
should be the same thruout the length of the knife. Tighten the 
two outside or end nuts as much as possible with the fingers, and 
then tap the knife gently with a mallet or block of wood until 
the exact measurement is obtained. 

The rear table, the one over which the work slides last, should 
now be so adjusted that it is exactly in fine with the edge of the 
knife at its highest point of revolution. This is important, for if 
too high, the stock will hit on the table edge and be stopped, and 
if too low, it will drop to the rear table at the end of the cut, making 
an uneven edge. To get the rear table and the top of the knife 
in fine, a try-square or straight piece of smooth, hard wood can 



ADJUSTMENTS OF WOODWORKING MACHINES 89 

be laid on edge on the rear table and allowed to project over the 
knife. The head can be slowly turned back and forth now, and 
the rear tabla raised or lowered until the knife just grazes the 
straight edge. It may now be found that the knife comes higher 
above the table at one end than it does at the other. This means 
that the table is not parallel to the knife. On all later machines, 
there is an adjustment which allows the level of the table to be 
changed by raising or lowering one side or the other. This should 
allow the table to Hne up with the knife. If the tables are not 
adjustable in the manner indicated above then the only alternative 
is that of Hning the knife with the table. The author has seen 
tables that were warped. To ascertain if a table is warped, put a 
straight edge or winding stick on each end of the table and sight 
over them. Two framing squares would do very well to sight over. 
This warping should be taken out by means of the sHding shoe 
adjustment or similar adjustment under each corner of the table. 

The next operation is that of getting the other knife to Hne 
up with both the ta.ble and the first knife. It is put in place 
precisely as was the first knife, care being taken to have it graze 
the straight edge, which is laid across the rear table, with the same 
friction as did the first knife. 

The final adjustment is that of getting the front table, over 
which the work first slides, in line with the two knives and the 
rear table. It is adjusted as explained for the rear table. It can 
be raised to the same height as the rear table and, by sighting or 
by stretching a line, one can determine whether they are lined up 
lengthwise or not, and by means of framing squares or straight 
edges, one on each table, the side ahgnment of the two tables with 
one another can be determined. While lining the tables with one 
another, the cutter head should be so turned that neither knife 
is at the top of the revolution and in the way of sighting. Of 
course when work is to be done on the jointer, the front table is 
lowered an amount equal to the thickness of cut that is to be 
taken from the stock. This adjustment is made with a wheel at 
the end of the table or on the side, and does not alter the condition 



90 SCHOOL SHOP MAINTENANCE 

that should exist between the two tables, namely that they should 
be true planes parallel to each other. These table adjustments 
must be so perfect that when stock passes over the knives it should 
be neither raised nor lowered even a trifle as it passes on to the rear 
table. Wherever possible, a belt from a jointer should pull down 
on the cutter head pulley so that there will be the least up-and- 
down motion to the knives, often caused by loose bearings or belt 
slap. 

85. The Surfacer. — The attachment for grinding surfacer or 
planer knives can not be adequately described here. Reference is 
made to one that fastens on the planer and grinds them without 
removing the knives from the machine. A finer and better ad- 
justment can be obtained this way than by the old method of 
removing the knives for grinding, and necessitating skill and much 
pains in getting the knives properly in place again. 

The old way, spoken of above, is one that must frequently be 
used, due to the fact that all equipments do not include the grinding 
attachments. For adjusting the knives after they have been 
ground and jointed, the following plan is followed: Two strips 
of accurately planed hard wood are placed between the bed, or 
table, and the rollers. These strips must be of exactly the same 
thickness and the thickness must be known by the operator. The 
table is then raised to such a position that, when the knives 
project from the cutter head about -^'^ or ^{2" they will just graze 
the strips of wood. At the same time the pointer, which indicates 
the thickness of stock being planed, should be adjusted so that it 
registers the thickness that the strips of wood measure. The nut 
at each end of the knives should then be turned tight enough to 
keep the blade from falhng out, and the other nuts left rather loose. 
The blades should be left out of the cutter head a slight bit more 
than the it" and gently tapped in with a mallet until they just 
graze the strips of wood evenly at each end. If the other nuts are 
tightened at first, too hard taps are required to make the knives 
move in the head, and when they do move they will, in all probabil- 
ity move so much as to throw the knives farther out of adjustment. 



ADJUSTMENTS OF WOODWORKING MACHINKS 91 

Great care should be taken, however, that all nuts and bolts are 
left tight before the machine is ever started, or serious injuries or 
damage may be caused. A thoro inspection should be made after 
it is thought that everything is in perfect shape. 

The rollers on the planer or surfacer should be so set that they 
will keep the stock moving steadily thru the machine, yet they 
should be no tighter than necessary to get this result. They are 
adjusted by tension springs which may be located by observation. 
Methods of tension vary on different makes of machines. All 
bearings should be wtII oiled at all times. 

86. The Mortiser. — The mortiser needs more care than 
adjustment. All moving parts should be kept clean and well 
oiled. One mistake, often made, is that of having the bits, in a 
hollow chisel mortiser, drawn up into the chisel so far that when 
the bit is revolved, unnecessary friction is caused between the bit 
and the very bottom of the chisel, and the latter is bulged at the 
bottom and the temper drawn. This is not necessary; it only re- 
quires a little care to keep the bit just free from the chisel when they 
are tightened in place. It must be remembered that the bit 
travels fast and that a little friction between the chisel and the 
bit will soon heat the chisel. 

87. The Band-Saw. — A band-saw is a simple machine to 
keep in shape, yet one that is often neglected. On all machines 
there is an adjustment that permits of Uning the wheels w^ith one 
another. This will, in most cases, be found on the upper wheel. 
Observation of how the saw travels on the wheels when it is running 
free of the guides, will tell whether the wheels are properly aligned. 
The saw should center both wheels when unhindered in its revolu- 
tion. The saw guide wheel should be so adjusted that it does not 
revolve when the saw is running idle and no work is being done 
by it. However, the guide wheel should be as close to the saw 
as is possible without being revolved by the latter. Under such 
conditions, one is assured that the saw is taking its own course 
over the wheels and will run true. Of course, when wood is pushed 
against the saw to be cut, the wheel should run. The jaws of the 



92 SCHOOL SHOP MAINTENANCE 

guide should be close together to prevent the saw from twisting 
too much, yet they should not pinch the saw. They should reach 
as far to the front of the saw as possible without interfering with 
the set of the teeth. That distance will be almost, but not quite, 
to the center of the teeth from the back edge of the saw. 

The chief causes of broken band-saws are poor tension on the 
saws, dull saws which will not do their duty, and poorly brazed 
joints. The tension should be such that the saw is taut and free 
from vibration, and yet is not subjected to undue strain. Dull 
saws mean that the work has to be forced against them so hard 
in order to be cut that the saw is under a strain which will generally 
cause trouble. Thick laps or brazes will cause friction between 
the saw guides and between the saw and the kerf in the wood, 
and will often cause the blade to snap. The laps should be filed 
until they are of the same thickness as the rest of the saw. The 
saw should also be straight where it is brazed. There should be 
enough set in the saw to allow it to follow a curve. 

88. The Lathe.— The lathe should be kept well oiled at all 
times. The Hve center should be sharp, so that heavy blows are 
not required to sink it into wood the proper distance for revolving 
the latter. Drill the wood for the center and make saw cuts thru 
the drill hole so as not to require so much hammering in order to 
sink the center into the wood, and thus save the bearing from 
abuse. The bearings should be kept tight at all times to insure 
a minimum of vibration both endwise and up and down. 

As a suggestion worthy of trial a sketch is shown in Fig. 73 
of a handy grinder that can be made in the school shop. It is 
intended for use on the lathe for grinding edge tools. It consists 
of a rraple arbor on which is mounted an emery wheel of the size 
desired. The wheel should have at least a l" face for edged tools. 
A keyway is made in the lead Hning to the arbor hole in the wheel 
and also in the arbor and a wooden key is driven in. A collar can 
also be made of wood and slipped on to the arbor, tight to the wheel, 
and be held in place by the key. One end of the arbor can be 
tapered to fit the opening for the live center in the head-stock, and 



ADJUSTMENTS OF WOODWORKING MACHINES 



93 



the other end made to fit the dead center. The tool rest can be 
used as a guide on which to steady the tools. A good saw gummer 
can be made by mounting similarly on a longer arbor an emery 
wheel that has the proper shaped rim for gumming. Care must be 
taken in holding the saw to keep it from binding and breaking the 
emery wheel, possibly to the discomfiture of the operator. 

89. Play in Bearings. — Bearings on the saw, jointer, surfacer, 
lathes, etc. should be free from much play or looseness. There 



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Fig. 73 




should b3 end play for the jointer and surfacer heads so that they 
can work back and forth as they revolve and a little play is not 
objectionable in the spindle of the lathe, as friction is thereby 
reduced, but the saw should have the least end play possible, 
to avoid over-heating the bearings. The looseness in machines 
Hke the lathe, saw, and small machines can be determined by 
testing with the hands, but on larger machines like the 12" jointer 
or the surfacer, it will probably be necessary to use a stick of wood 
as a lever because of the weight to be lifted. Otherwise, one might 
be misled into thinking the bearings were tight when the real 
difficulty was that the weight made it impossible to detect the 
looseness without a lever. 

Between the halves of the bearing should be found shims of 
thin material. When it is decided that a bearing is loose, these 



94 SCHOOL SHOP MAINTENANCE 

thin pieces of shimming stock can be removed until the play is 
reduced. The amount taken from each side of the bearing should 
be equal. The bearing bolts should then be snugly tightened. 
If after this, it is found that the bearings are too tight, some of 
the shimming material should be replaced, for it is not a good plan 
to make the bearings free on the shaft by loosening the bearing 
bolts. They should be tight at all times and the amount of shim- 
ming material between the bearings should decide the play of the 
shaft. 

Bearings on some makes of lathes are adjusted with special 
devices. Instructions for adjusting these are furnished with the 
machines. The end play in saws is adjusted in different ways, the 
common method being that of turning a collar on the shaft. This 
collar can be locked when properly adjusted. 



APPENDIX 

Organization of the Preceding Material 
FOR Teaching Purposes 

The subject-matter presented in the preceding pages can be 
used as a basis for training vocational and manual arts teachers 
who may be responsible for the planning and instalHng of their 
school equipment and who surely are expected to keep it in good 
running order. Much of this material can also be used by teachers 
in instructing students in vocational classes about such work as 
saw fitting, machine adjustments, repair of belts, etc. 

The most effective use of this subject-matter would be that of 
the laboratory-class method where much supplementary material, 
other than the text, might be used, combined with reading assign- 
ments and class discussion. 

The plan of organization to be suggested in the remaining few 
pages is ample for a full 40 weeks' course of six to nine hours of 
work each week, and even then, some of the work covered would 
need to be dealt with rather superficially. In this last statement, 
reference is made to the use of the material for teacher-training 
purposes. 

The order of topics, as given in the preceding pages, is not 
necessarily the best order in which to present the matter for 
instruction purposes. In fact, it is doubtful if the student should 
study installation and shop planning problems until he has become 
familiar with the machines and equipment thru maintenance 
work on them. 

The following plan of organization is for teacher-training 
purposes and is suggestive only: — 

1. Fitting Edge Tools — Application on the regular edge tools of the 
shop. 

2. Fitting S'aws — The first work may well be done upon strips of soft 
steel as indicated in the text so that students get actual lay-outs 

95 



1 SCHOOL SHOP MAINTENANCE 

of teeth by use of the bevel, protractor and scribe. Saws, badly 
out of form, are the most difficult to work upon, and should be 
given to the students last. 

3. Belting — Short pieces of belting of the several kinds and widths 
should be provided so that the various methods of lacing can be 
practiced. These pieces may be used repeatedly, and when the 
holes become badly worn, the ends of the pieces may be cut and 
new holes punched. In case it is inconvenient to provide pieces 
of belting or in case it is wished to supplement them, methods of 
lacing may be practiced by means of the Standard Belt Lacing 
Card. Holes may be punched in the proper places in the cards 
and shoe strings or cord used for lacings. Samples of various 
patent lacings may be procured from manufacturers. 

4. Brazing Band-Saivs— Odd pieces of broken saws may be used until 
students become sufficiently proficient to make brazes on the regu- 
lar shop saws. 

5. Adjustments — To be performed on the regular shop equipment if 
needed. If not needed, the methods for making the adjustments 
should at least be demonstrated. 

6. Babbitting Bearings — Old boxes and arbors or pieces of shafting, 
or in an emergency, pieces of pipe filed smooth, may be used. For 
the first lessons, these pieces may be supported by wooden V 
blocks on the benches or table. Later, bearings in actual use 
should be poured and fitted. 

7. Power Transmission in a School Shop — The material in this chapter 
can be assigned for study and class discussion. For more detailed 
study and reports, the references given in the bibliography may be 
assigned. Examples or illustrations of various hangers, pulleys, 
etc. may be provided and actual problems in installation may well 
be undertaken. 

8. Motors and Currents — For study and class discussion mainly. More 
detailed technical information may be obtained by use of the refer- 
ences given. 

9. Installation of Metalworking Machines — For study and class dis- 
cussion. Actual work in installation should be given students if 
possible. 

10. Installation of Woodworking Equipment — For study, class discus- 
sion and practice; if possible, by actual installation of equipment. 

11. Shop Planning — Altho no space is given to treatment of this 
subject as a separate unit in the preceding pages, yet all discus- 
sions on installation bear directly on planning the shop. An actual 
problem of shop planning may be assumed and the details worked 



APPENDIX 97 

out and applied in the form of drawings on large sheets of cross- 
section or drawing paper. These drawings should be made to 
scale, }i" to the foot being a good scale for this purpose. Later, 
details of shafting, pulley and belt plans may be drawn, and, if 
time permits, lists of equipment giving numbers, sizes, types, 
costs, makes, etc. may be compiled. In attempting the shop- 
planning problem, as indicated here, much time will be necessary, 
and it should not be attempted until the student has familiarized 
himself with the material on installation and maintenance. If 
actual planning problems for solving can be obtained, and the 
installation of some of the equipment can follow the planning, then 
the very good contact between theory and practice should result 
in a group of individuals thoroly prepared to solve almost any school 
shop installation and planning problem. 



INDEX 

(numbers refer to pages) 



Adjusting 

band-saw 

circular-saw 

jointer 

lathe 

mortiser 

surfacer 

Aligning 

hangers 

pulleys 

shafting 17, 

B 

Babbitt 

aligning for 

damming box for 

formula for 

melting 

oil grooves in 

pouring 

preparing to pour 

scraper for 

scraping 

shims 

Band-saw 

adjustments to 

brazing 

filing laps on 

fitting 

Bearings 

adjustments to 

babbitting .• • • 

Belting 

care of 

cemented splices in 



91 

88 
88 
92 
91 
90 

17,18 
20 

18,78 



79 

81 
77 
82 
81 
82 
78 
86 
85 
84 

91 

57 
57 
52 

93 

77 

62 
73 



Belting, choosing 61 

clamp for lacing 63 

compared 61 

direction of 65 

dressings for 62 

how applied to pulleys ... 64 

lacing with rawhide 66 

patent fasteners for 71 

splicing 66 

stretching 63 

rules for finding horse-power 

of 75 

Bevel 

on chisels 42 

on hand-saw teeth 51 

on plane irons 39 

on turning tools 42 

Blower 31 

Boxes 

open and closed 82 

damming 81 

Brazing band-saws 57 

bunsen burner for 60 

use of blow torch for ... . 60 

using tongs for 59 



Chisels, fitting 42 

Circular cross-cut saws 

care of 88 

gumming 56 

shape of teeth of 56 

speeds of 37 

Circular rip-saws 

filing 54 



98 



INDEX 



Circular rip-saw?, gage for. . . 55 

layout of teeth 53 

saw clamp for 54 

setting 55 

side-dressing 55 

template for 55 

Couplings for shaft 21 

Cross-cut saw, fitting .51 

Crown in saws 48 



Draw knife, fitting 43 

Drill press, installation .... 30 



Emery wheel, speeds of ... . 36 



Forge 31 

Formulas 

babbitt 77 

distance apart of hangers . . 16 

horse-power of shafting . . 12 

sizes and speeds of pulleys. . 22 



Hangers, fastening 18 

formula for spacing 16 

for aligning shafting .... 10 

types and selection of ... . 15 

Horse-power 

for woodworking machines. . 37 

of belting 75 

required for group drive. . . 9 
transmitted by cold rolled steel 

shafting 11 

turned steel shafting .... 13 

I 

Individual drive, compared to 

others 7 

Installation 

anvil 31 

blower 31 

drill press 30 

forge 31 

lathe 30 

milling machine 30 

planer 28 

shaper 31 

woodworking equipment. . . 33 



Gouges, fitting 44 

Grinding, plane irons 40 

Group drive, compared to others . 7 

H 

Hand rip-saw 

angle of teeth 47 

clamp for filing 48 

how to file 48 

jointing 49 

setting 49 

side-dressing 50 

Hangers 

alignment with taut line. . . 18 

alignment wit'h transit ... 17 

distance apart and where placed 16 



Jointer, adjustments to 
Jointer, home-made saw 
Jointing hand saws . . 



Keyhole saw, filing 



88 
49 
49 



52 



Lacing belts 

with rawhide 66 

alligator steel lacing 72 

Blake's belt hooks 73 

cemented splices 73 

clipper lacing 71 

rubber and canvas belts. . . 69 



100 



INDEX 



Lathe 

adjustments to 92 

installation of 30 



M 

Metalworking equipment, instal- 
lation of 28 

Milling machine, installing. . . 30 

Mortiser, adjustments of . . . 91 

Motors 

advantages of A. C 25 

advantages of D. C 25 

advice concerning 24 

care of 26 

causes of sparking of D. C. . 26 

data necessary for choosing . . 25 

installation of 26 

planning for 26 

P 

Pitch, hand-saw teeth 51 

Plane irons 

bevTl on 40 

grinding 40 

whetting 41 

Planer 

installation of 28 

levelling 29 

Planer and jointer knives, fitting 46 

Power transmission, discussed . 1 

Prussian blue 86 

Pulleys 

alignment 20,35 

placing 21 

t3^es compared 20 



Scraper 

home made babbitt. . . . 

sharpening cabinet .... 
Set collars, where placed. . . 

Setting hand-saws 

Shafting 

aligning for babbitt. . . . 

alignment first time . . . 

alignment second time . . 

couplings for 

distance apart of 

position of 

preparing shaft for pouring 
babbitt 

selection of 

speeds of 

Shaper, installation of . . . . 
Shims, in babbitting .... 
Side dressing handsaws . . . 
Spoke shave blades, fitting. . 
Surfacer, adjustments to . . 

T 

Tables 

distance of hangers apart . 

emery wheel speeds. . . . 

horse-power of shafting . . 

speeds of machines .... 
Teaching, using this book for 
Turning tools, fitting . . . 

W 

Whetting plane irons 41,42 

Woodworking equipment 

installation of 33 

horse-power for 37 

spaces necessary for .... 33 

speeds of various machines. . 36 



45 
19 
49 

78 
17 
18 
21 
14 
14 

80 
10 
11 
31 

84 
50 
44 
90 



17 
36 
12 
36 
95 
42 



